EDITOR’S NOTE: This blog post has been updated with more tactics and links to benefit our readers

Original Post Date: January 26, 2016

Have you ever thought of Retargeting as playing fetch with a dog?

The goal is always to bring the ball back. Just like your lost visitors and conversions.

Now you may not have a dog, or a retargeting campaign, yet. But you know that getting good at something takes practice and experience.

Retargeting is no different.

So right now, I want to share 33 different types of retargeting campaigns that we run for our own clients and how you can run them too.

But first…

What Is Retargeting & Why Should You Care?

Let’s take a common example:

A visitor hits your website or landing page without converting. You then add a cookie/pixel to their browser or capture their email address to then have your image ads, text ads, or emails follow them around the rest of the web until they hopefully come back and convert.

That’s retargeting in a nutshell.

Some people also call it remarketing. For the sake of clarification, they’re essentially the same, although Google calls it remarketing.

Now to the fun part:

If done right, retargeting can outperform all other digital ad channels.

CMO.com published 15 mind-blowing stats on retargeting that almost had me pee my pants. (I drank a lot of water and coffee that day):

• Retargeting can bring the highest lift in brand searches by 1,046%
• The average CTR is 10x higher than that of regular display ads
• Retargeted visitors are 70% more likely to convert compared to ones who aren’t

A Quick Disclaimer

As you can see, it’s easy to know that retargeting works. It’s a lot harder, though, to actually make it work.

Now, don’t get me wrong. Grouping all your visitors into one Audience and hitting them with the same message can definitely get you conversions. In fact, that’s what many people do.

You don’t have to be perfect about retargeting, but if you are interested in taking your efforts to the next level, then keep reading.
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Retargeting Campaign Goals

There are two basic goals you can set for your remarketing campaigns.

• Awareness – These campaigns are used to be informative rather can conversion based. These campaigns are usually directed to visitors that haven’t yet interacted with your business, mostly being used to stir up some interest in your businesses products, features, and announcements.
• Conversion – Conversion based campaigns obviously bring the most value to your efforts. These campaigns are used for visitors who are more familiar with your brand’s products/services, but haven’t yet converted. You want the visitors to click on an ad, direct them to a landing page, where you can convince them to make the desired conversion action.

Now, let’s dive into the different types of retargeting campaigns that you can take advantage of, as early as today.

1) Sequential Retargeting

Do you have a long sales cycle? Or do you have a complex buying process with multiple touch points? If so, then sequential retargeting could be huge for you.

Just like email nurturing pushes visitors down the conversion funnel, depending on what emails are opened and clicked through, sequential retargeting works the same way.

You group your audiences in different categories or lists and include/exclude them depending on the landing pages, durations, or downloads they’ve been taking action on.

A new set of ads with new messaging appear when those actions are taken. These ads get the visitor to take the next step in the conversion process, while excluding them from the old set of ads.

Just like a regular Google Analytics goal funnel, you can use sequential retargeting to create more touch points. It also shows where your bottlenecks are in the conversion process so you can fix them.

To see what your different ads could look like, take a peek at this example from Pagewiz:

As you can see, the first ad is trying to get the sale as fast as possible. If that doesn’t happen within a certain amount of time, then the sequential ads are pushed live one by one.

Quick Recap:

Sequential retargeting is the practice of varying the ad copy and messaging depending on where the visitor is in the conversion process, with the end goal of pushing them along.

Your goal as the advertiser is to use education, features, and/or benefits to eventually get them to buy.

2) Time Delayed Retargeting

If you run any type of cookie/pixel based retargeting, then there’s a good chance that your audience eventually has an expiration date (Google has a max time of 540 days for example).

But in this case, time is your friend, not your enemy.

Similar to sequential retargeting, time delayed retargeting basically works this way without the need for action from the visitors:

• First Week: All visitors see ad #1
• Second Week: All visitors see ad #2
• Third Week: All visitors see ad #3
• Fourth Week: All visitors see ad #4
• etc.

Benefits Of Time Delayed Retargeting

The best thing about time delayed retargeting is that you don’t need accompanying landing pages or collateral to back up everything your ad says. Although it won’t hurt if you do.

If you only offer one service, like how our PPC agency offers PPC management, then you can use your different time delayed retargeting ads to showcase different perks and values of working with you.

In fact, if you already have an email nurture campaign, you can take the subjects of those emails and turn them into retargeting ads. Here’s an example of how we could do it since our #1 goal is to get people to request a free proposal from us.

• First Week: Example proposal
• Second Week: Screenshots of Google Ads improvements
• Third Week: Types of packages we offer
• Fourth Week: Resources of thought leadership
• Fifth Week: Case studies
• Sixth Week: Example proposal
• etc.

For one of our clients, we decided to break up the audiences in monthly periods of 1-30 days and 31-60 days. Here are the results:

As you can see, the 1-30 day campaigns and image ads are performing the best. The interesting thing is that both 1-30 and 31-60 have different offers, but none that are different in threat levels or channel temperatures.

What I mean by this is that the lead magnets in these campaigns are very identical since they’re both PDF guides. We could ask for a bigger conversion commitment in the 1-30 day campaigns since they have the highest performance so far.

Quick Recap:

The longer visitors have been part of your time delayed retargeting campaign, the bigger the offer/incentive they need to act.

You may find that for the first two weeks (depending on your conversion cycle) your ads are just product/offer specific with your logo and unique value proposition.

For the next two weeks, you may offer a bonus or 10% discount to get them to act. A burn pixel can exclude past visitors who have already converted so they don’t see the discount ads and complain.

3) Offer Change Retargeting

If you’re in the unfortunate bucket of having 98% of your visitors not convert after the first visit, don’t fret. You could be in luck.

What I mean by that is that it could be your initial landing page offer/call-to-action that’s holding you back.

There’s a reason people choose not to convert, especially in lead gen situations. Often it’s because the offer was too threatening, or you didn’t do a good enough job explaining the value of the offer.

In other words: They may not be ready for a free consultation or free proposal just yet.

You can use your retargeting ads to drive more conversions when this happens. Retargeting can also serve as a research tool to find out if you should change your initial landing page offer.

Let’s say that your initial landing page offer from search network PPC traffic is a free consultation that has a 2% conversion rate (only 2 out of 100 visitors want your consultation).

To retarget to the other 98%, you can pick an idea from the list below as your educational lead magnet, to bring them back to eventually want a consultation.

Quick Recap:

There’s a reason why most people don’t convert on your site or landing page.

It could be that you’re not explaining the value of your offer well enough, or, it could that a different offer will work much better for you.

Remember: Visitors have options, and you’re not the only one who offers that product or service. Take the time and effort to educate and nurture.

4) Up-Selling Retargeting

Have you ever heard the saying “a buyer, is a buyer, is a buyer”?

It took me almost five years from hearing it, to actually understanding it.

What it means is that if someone has already bought from you, then they’re much more likely to buy from you again.

In fact, 41% of overall eCommerce revenue in the US is from repeat shoppers.

And that’s not even the crazy part.

What’s The Crazy Part?

Thanks for asking.

According to Adobe, repeat buyers are likely to spend 5x more than first time shoppers.

Here’s an email retargeting example from Amazon showing which cameras you can upgrade to.

But what if you’re not an eCommerce shop?

If you’re in the lead generation business, then repeat buyers could mean referrals in the form of leads as you often see for service-based businesses.

You can essentially create new retargeting audiences by targeting people who have visited your post conversion pages with new offers in the forms of upgrades or complimentary service add-ons.

Quick Recap:

When visitors buy from you, it’s because they trust you.

Don’t feel greedy or ashamed to ask them to convert again and to buy something at a higher price. If your products and services bring value, they’ll be upset if you keep them secret.

5) Down-Sell/Cross-Sell Retargeting

Okay, maybe your visitors don’t want to buy more from you.
If that’s the case, then showcasing a different offer from their recent “No Thank You” on the up-sell offer could make a lot of sense for your retargeting campaigns.

Let’s say that we get you on board for our PPC services. Our next logical step as an agency would be to offer our landing page services as a cross-sell to you.

The beauty of this is that a true cross-sell is something that’s complementary to the original thing your visitor converted for, and it should help the performance of it too.

If we wanted to down-sell our landing page service, then we could potentially offer a free guide on it, with the goal of converting them in the future.

Quick Recap:

If someone buys an orange, up-sell a juice presser.

If someone buys the juice presser, cross-sell a recipe book.

And if someone doesn’t buy the juice presser, down-sell them an orange peel artbook.

6) Layer Retargeting (Google Analytics Features)

Have you ever thought of using Google Analytics data to create unique remarketing audiences?

If not, then here’s something new to take advantage of.

In a recent case study from ThinkWithGoogle, Periscopix helped UK merchant Watchfinder create over 20 unique retargeting audiences. They were split between location, languages, and on-site behaviors like cart vs non-cart visitors and time on site.

They also found that certain internet service providers from the London financial district showed interest in their products. Watchfinder used that information to target visitors from banks like JPMorgan and Goldman Sachs.

After just six months, ROI from the retargeting campaigns proved to be around 1,300%. Average order values increased 13% as well, ultimately leading to a 34% reduction in cost per acquisition.

Quick Recap:

Additional insight from Google Analytics, like time on site and geography, can create unique retargeting audiences to target.

The more data points you have on certain visitors, the easier it will be for you to determine how likely they are to convert from your ad messages.

7) Page Value Retargeting

Each page on your website has a different value when it comes to retargeting ROI potential.

Picture a visitor who has only visited your homepage and no other pages (like you’ll often find when you look inside Google Analytics). There’s a good chance that targeting them with retargeting is a waste of time, money, and impressions.

From single page bounce visitors to people who have been on your site or landing page for say, 2 minutes plus, it’s important that you spend and bid proportionally with those thoughts in mind.

Paying an average of $1.00 a click for an audience that has been on site for 2+ minutes will usually pay off quicker than paying an average of $0.50 for all visitors.

In addition to the value of these different audiences, you’ll also find that they are more likely to convert on different retargeting offers.

People who have bounced from the homepage are more likely to convert on a soft/less threatening offer like an eBook download, compared to 2+ minute visitors who might be okay to convert on a free proposal offer.

Quick Recap:

Look inside your Google Analytics dashboard and find which pages on your website hold the most attention. Sometimes this is a demo page or the about page.

Once you’ve identified them, you can add layers like page URLs, time on site, and geography to help craft ads tailored to that audience.

8) CRM Retargeting

Customer Relationship Management (CRM) tools keep a lot of companies’ leads and prospects in order.

This type of retargeting campaign doesn’t actually need cookies or pixels to retarget. It runs on email addresses.

By exporting your CRM email list to a retargeting platform like AdRoll, you’re able to match the email addresses to social media accounts and other platforms like Gmail. These platforms already know when the email address owner is logged in.

In Retargeter’s case study with Total Wine, they used CRM emails to create unique audiences/segments for specific retargeting ad offers.

That gave them a:

• 12.9% ROI
• 38% conversion rate (for eCommerce, mind you)
• 320% extended web reach.

But what if you don’t use a CRM?

You can export emails from email providers like MailChimp, or even a list you already have. You can also rent email lists from publishers who have your target audience. (Many financial institutions do this already.)

Quick Recap:

Your CRM potentially holds a motherload of information about the behaviors of your visitors. Use that data to create unique audience groups to then retarget to.

Many times, you’ll find the best uplift in performance from targeting old users/visitors that were once hot. This could help reignite them.

9) Bulk Email Retargeting

Staying on the topic of emails, you also have the option to target your email list directly through Google Ads, Facebook, or Twitter.

Google Ads has a feature called Customer Match. Facebook as a feature called Custom Audiences. And Twitter has a feature called Tailored Audience. All of these can help you reach your email list effectively.

The biggest thing to keep in mind when it comes to bulk email retargeting is the “match rate” of emails to users on a given platform.

Match types between Google, Facebook, and Twitter typically break down like this:

• Google = 50.4%
• Facebook = 48.99%
• Twitter = 10.2%

As you can see, the behemoths of the ad world (Google and Facebook) have such a strong match rate because of the usage of their platforms. Whereas not as many people are on Twitter (or use an email address that matches).

Once you’ve decided on which platform to use (maybe multiple), you can take advantage of the different types of ads and networks (especially on Google) to get your email list to convert.

Quick Recap:

Just like any retargeting campaign, don’t forget the power of segmenting your audience into specific buckets. Targeting all emails with the same message won’t be as powerful as it could be if you split things up.

10) Individual Email Retargeting

You can add a hidden HTML image tag to your emails that attaches a cookie/pixel to the browser of the person who opened that email.

One of my favorite tools for creating this type of retargeting campaign is SiteScout.

If you’re running promotions with your email campaigns, then you can create an additional ad set to follow people who have opened that email to amplify the promotion.

The retargeting ads also give visitors quick access to the promotion. Otherwise, they’ll have to go back to the original email and click the link there.

Remember that this only works with web-based email providers like Gmail and Hotmail. You want to make sure that the email recipient is allowing images to show in the email you send.

Adding other actual images to your emails also gives the recipients have a reason to allow them to show, now and in the future.

Quick Recap:

If you want to squeeze the most ROI from specific email marketing campaigns, then strongly consider using hidden HTML image tags as retargeting codes.

This will allow you to message match your email to the retargeting ads to reduce the time to convert.

11) Similar/Lookalike Audience Retargeting

When you’re creating retargeting audiences from your landing page and site visitors, PPC networks like Google Ads and Facebook can create similar audiences that show the same intent and browsing behaviors as your own list.

Through hundreds of different factors, you can target these similar audiences as regular retargeting campaigns, even if those people being targeted have never been on your landing page or site.

Google Ads calls it similar audiences and Facebook calls it lookalike audiences.

Once you start creating your retargeting list from your own visitors, Google and Facebook will automatically create similar and lookalike audiences for you to take advantage of.

A lot of improvements have been made since Google first introduced similar audiences back in 2013, and today, you can expect around 40% increase in conversions using a feature like this.

Quick Recap:

Sometimes a similar/lookalike audience is much bigger than your original retargeting list.

Take advantage of it, but tread lightly. Your specific industry can have varying performance when it comes to how accurate and similar the borrowed audience truly performs.

12) Push-Along Retargeting

Do you have a conversion funnel with multiple touch points where visitors need help moving to the next step? If so, then push-along retargeting can be your new best friend.

Just like certain keywords can be tracked as to how far down the conversion funnel a visitor goes, you can do the same thing with your retargeting ads.

The goal here is to craft ads that hint to the next step the audience should take to get further down your conversion funnel.

Like sequential retargeting, push-along retargeting focuses on actions taken by the visitor in relation to the next step in the conversion process. No time or other external factors are incorporated.

This is usually a stellar retargeting campaign tactic for SaaS onboarding issues.

Quick Recap:

Make sure your audience sizes are big enough for each step of your conversion funnel.

If you have less than 1,000 visitors in each step of step of your conversion process, then you may not get enough impressions, clicks, or conversions.

13) Geographic Granularity Retargeting

You may be advertising nationwide or even internationally, but that doesn’t mean your retargeting ads should do the same.

If you look inside your PPC account, you should be able to see the geographic locations of where your visitors are coming from.

Pair that data with geographic specific retargeting ads, and you could see a 53% increase in conversion rates like Mazda did.

With a mix of offline and online insight, Mazda was able to use IntelliAds from the Merchenta retargeting platform to “drive” (pun intended) more people into local showrooms based off the car models they were looking at online.

The crazy thing is that the average car sale value traced back to ad impressions was 98% higher than the offline average.

Now, you might not be a car brand. But that shouldn’t stop you from taking advantage of this tactic.

You can create retargeting ads that are specific to the geography of your retargeting audience. Pair that with a landing page optimized to follow the message match and you could produce higher retargeting metrics.

Quick Recap:

Pick the geographies that have the highest audience count first and start there. The more impressions you get, the higher your chances are for clicks that turn into conversions.

Once a success, repeat the process by creating unique retargeting ads and landing pages from the next highest visitor geography.

14) Redirect Link Retargeting

Ever wish you could retarget people that land on URLs or pages that you don’t control?

Well, you kinda can, and it’s called redirect link retargeting.

Redirect link retargeting allows you to add anyone who clicks a specific link to a specific retargeting audience.

This type of retargeting can work great in a few different scenarios:

1. Your site is a comparison site of multiple options where you’re potentially making money off referral conversions. Creating retargeting ads could help get you more conversions.
2. If your company has uniform email signatures, then you can track clicks on certain links and create unique retargeting audiences that way.
3. You can also do this within forums, blog comments, or author bio links in guest posts.

As you can see, there are tons of options and you can even use a secure SSL variation of it as well.

Quick Recap:

Redirect link retargeting is perfect for people and companies to try and cookie visitors who are going places they don’t control or own.

15) RLSA Retargeting

Remarketing lists for search ads (RLSA) is a Google feature for creating specific text ads exclusive to specific retargeting audiences.

RLSAs also allow you to set bid modifiers across search and shopping ads. With these, you can bid more aggressively or passively depending on searches from people who are on your audience list.

One of my favorite use cases for RLSA is when you’re for competitive industries. Let’s say you want to bid on competitor names, but only want your ads to show if the visitor has been on your site before (shoutout to LunaMetrics for the idea).

Maybe the visitor was comparison shopping you in the past but never converted (on your site or your competitors’). A month later, they’re researching your competitors by typing in their names to Google.

RLSA audiences can be targeted broadly by keyword selections, among other advantages.

• RSLAs brought World Travel Holdings a 300% increase in conversion rates and 30% increase in ROI. They targeted broad match keywords like “present” and “gift” in addition to their own brand terms.
• A tire company in Germany adding in positive bid modifiers to people who have been on their site in the past but didn’t convert. Total sales increased 22% and conversions up 163%.
• A Telecom company customized ad text depending on previous pages visitors have been on. They saw cost per conversion drop 66%.

Long story short, RLSA works wonders for search network targeting.

Quick Recap:

To get your feet wet with RLSA, use regular bid modifiers by adding in your retargeting audience. Select “Bid only” from the “Target & Bid” option. This allows you to be a little more aggressive (or less aggressive) with people who have already been on your site.

16) Anti-Bounce Retargeting

This point is more of a retargeting tactic and not a standalone retargeting campaign. (But it could be if you’d like.)

If you take a look at your Google Analytics account, I’m sure there’s one metric you’re sort of obsessive about, and that’s bounce rate.

Now consider your retargeting audience.

If you have a bounce rate between 60-80% or higher, then why would you put 60-80% of your retargeting budget towards people who weren’t even remotely interested in what you have to offer?

See where I’m going with this?

To make this happen, you’ll want to create a “cookie insertion delay” of a certain amount of time (like 60 seconds or higher).

It will then only cookie visitors who have been on the site or landing page for at least that amount of time.

Quick Recap:

A bounce isn’t necessarily a bad thing.

This tactic is especially great if you have an isolated landing page (with no external links) where all exits are considered as bounces.

17) Non-Cookie Retargeting

As marketing technologies continue to improve and make lives easier for us marketers and advertisers, you’ll find that the old methods of cookie/pixel based retargeting will quickly become obsolete.

Since more people are using mobile devices with browsers that are inherently “anti-advertising” (damn you iOS 9!), it’s easy to see how regular cookies may expire or get deleted relatively quickly. And while still in its infancy, non-cookie based retargeting is becoming more and more popular.

If you find that your current retargeting cookies might not be working the way they should, then consider looking at these options:

Fingerprint retargeting is similar to device ID retargeting. Certain identifiable pieces of information are used to identify a visitor across different devices.

Without the need for cookies or pixels, advertisers can narrow down cross-device retargeting through data like browser types, installed software, time zones, IP addresses, and more.

Quick Recap:

Know why Google was so in love with the idea of a social network?

Because companies like Facebook are leading the pack in the ability of cross-device retargeting. They can do this because you’re most likely logged into your Facebook account on desktop and mobile devices.

18) Dynamic Retargeting

Dynamic retargeting helps you create image ads at scale so you don’t have to individually create hundreds or thousands of product/offer specific image and text ads.

In the example GIF below, you can see the difference and depth of detail and dynamic retargeting ad could have.

If you’re an online retailer with hundreds or thousands of products, then you can use ad templates from providers like Google Ads or AdRoll that grab info like product images, pricing, and availability from your shopping feeds.

The retargeting cookies take note of which product pages you’ve visited. Your dynamic retargeting ads only show products that you’ve shown interest in.

This type of retargeting can also be used in the travel or hospitality industry for showcasing dynamic ads based on travel routes or vacancies.

Quick Recap:

Google Ads and other retargeting vendors like AdRoll allow you to create dynamic retargeting ads that instantly showcase ads on the Google Display Network and inside social networks like Facebook and Twitter.

You can then use time-delayed retargeting to showcase stronger offers/discounts depending on the length of the visitor being part of the retargeting audience.

19) Content Retargeting

Are you investing quite a bit of money into content marketing?
If so, then a content retargeting campaign could be a great way for you to earn trust and gain conversions in the future.

Here’s how it works:

• Create a retargeting audience to target people who have been reading a certain blog post or content piece on your site.
• Retarget people who have shown interest in your offer or product.
• You create image and text ads that showcase a complementary piece of content, a piece of content they might like, or better yet, a soft sell/low threat offer like a free guide.

Here’s an example from Rubicon Project’s Dax Hamman on the AdExchanger blog:

“A consumer who is looking for information on picking the best mortgage visits citimortgage.com. They could be retargeted with a recommended link, “5 things to watch out for when deciding on a mortgage,” by Citibank on usatoday.com/money.”

In the example above, Citibank is actually sending visitors to a co-promoted piece of content on USAToday. Something you can do with Forbes BrandVoice as well.

But if you’re not looking to shell out at least $50,000 to make that happen, then you can always bring the retargeted visitor back to content that’s hosted on your own properties.

Quick Recap:

Content retargeting is mostly used to nurture and increase the trust between the visitor and the brand. It doesn’t necessarily have the goal of a direct conversion like so many other retargeting campaigns do.

Content retargeting works especially well for industries and verticals that have long buying cycles (i.e. the conversion isn’t cheap to the visitor).

Having your brand front and center with the goal of educating the visitor instead of getting them to buy can make you come across much more trustworthy than your competitors.

20) Referral Retargeting

You got your visitor to buy, but the up-sell, cross-sell, or down-sell didn’t do so well.

What if your visitor knows another person who could benefit from your product or service? Wouldn’t you want them to let their friends or network know about you?

Of course you do.

When you get people to convert, you create a new audience from your post-conversion URL that groups the audience into a “referral bucket”.

Your image and text ads then showcase a message of what’s in it for the referrer (like, get 10% off every person that you invite who joins), and then you have a dedicated landing page, and this is vital, that makes it super easy for the person who has already converted to send the link to their network.

When it comes to referral retargeting, you can get inspiration from a lot of “coming soon” landing pages, or look at companies like Uber and Lyft who crush when it comes to referral marketing.

Quick Recap:

Your business type determines the type of referral virality you can expect.

B2C companies usually have great reach and potential compared to B2B companies who deal with lower customer volumes.

21) Social Retargeting

As a retargeting opportunity that all advertisers and marketers should be taking advantage of, social retargeting should definitely be higher up on this list.

Although you can create specific retargeting audiences within social platforms like Facebook and Twitter, I tend to go with retargeting providers that allow me to target multiple networks within one dashboard.

AdRoll is one of the leaders of social retargeting, along with Perfect Audience, Criteo (and others), that allow you to retarget your visitors on Facebook, Twitter, and other publisher websites.

LinkedIn also has their own retargeting solution called Lead Accelerator that you can use for retargeting on their network.

Quick Recap:

Many traditional PPC channels like Google Ads and Bing Ads don’t have access to ad inventory on social networks.

Go directly to the social network or use 3rd party tools to keep as many of your campaigns under one dashboard.

22) Competitor Retargeting

You read that right, and there’s a way to do it.

AdRoll, Quantcast, and Google Ads all offer the ability to target audiences that have shown intent or browsing behavior that took them to competitor sites. (Almost like the “similar audiences” we’ve covered earlier in this post!)

There’s also a tool called ReTargeting BASE that has a solution called “Pre Retargeting” that states it can add cookies to visitors who visit competitor sites.

Is it ethical/legal to use that type of service? Probably not, but I’m sure some people have been tempted to try. You can read this Reddit thread from a person who asked the right questions.

In addition to what’s mentioned above, you can use these Google Ads tactics as well:

• RLSA targeting by using competitor names as keywords
• Gmail Sponsored Promotion (GSP) ads bidding on competitor domains as keywords
• Google Search Network w/ Display Select campaigns – this helps you showcase display ads based on keywords that have been typed into Google as a prerequisite for your display ads to show.

Quick Recap:

No respectable ad platform will launch a competitor retargeting solution in it’s purest sense (being able to have your retargeting code on competitor sites).

But there are ways you can mix and match to get similar/desired results.

23) Partner Retargeting

Also known as “let’s share each others retargeting pixels” retargeting, partner retargeting is basically the partnership between two sites that allow each other’s pixels to be used.

You may find that a website that only sells ketchup would be interested to retarget visitors from a site that only sells mustard, and vice versa.

As a better (and more realistic example) you could find partner retargeting happen between airlines and hotels. Both are separate companies but have complementary offers that usually go hand-in-hand.

Perfect Audience has a tool named Connect that allows you to do just this.