Search engine optimization (SEO) is the process of improving the volume or quality of traffic to a web site from search engines via "natural" or un-paid ("organic" or "algorithmic") search results as opposed to search engine marketing (SEM) which deals with paid inclusion. Typically, the earlier (or higher) a site appears in the search results list, the more visitors it will receive from the search engine. SEO may target different kinds of search, including image search, local search, video search and industry-specific vertical search engines. This gives a web site web presence.

As an Internet marketing strategy, SEO considers how search engines work and what people search for. Optimizing a website primarily involves editing its content and HTML and associated coding to both increase its relevance to specific keywords and to remove barriers to the indexing activities of search engines.

The acronym "SEO" can also refer to "search engine optimizers," a term adopted by an industry of consultants who carry out optimization projects on behalf of clients, and by employees who perform SEO services in-house. Search engine optimizers may offer SEO as a stand-alone service or as a part of a broader marketing campaign. Because effective SEO may require changes to the HTML source code of a site, SEO tactics may be incorporated into web site development and design. The term "search engine friendly" may be used to describe web site designs, menus, content management systems, images, videos, shopping carts, and other elements that have been optimized for the purpose of search engine exposure.

Another class of techniques, known as black hat SEO or spamdexing, use methods such as link farms, keyword stuffing and article spinning that degrade both the relevance of search results and the user-experience of search engines. Search engines look for sites that employ these techniques in order to remove them from their indices.

My point of view: 

Most people – ok, almost everyone outside the SEO industry – equate SEO with getting the #1 ranking for your website in Google.

But SEO is much more than that. There are 3 main steps in the SEO process:

First, like any business, you need to identify your audience (your target market). Not only are you setting your website’s goals and profiling your audience, at this stage you are also scouting your competition and evaluating what you need to do in order to ‘dominate’ this particular sector.

Second, you take steps to get your website rank as high as possible in the search engines for those keywords that this audience is most likely to use. This involves things you do to the site itself (if you are setting up a new website then you should ensure that it is search engine friendly from the ground up). It also includes off-site activities which are all geared towards the process of having other websites link to yours.

Third, you constantly track your website’s progress in the search engines and make adjustments to your SEO strategy as necessary.

While we define SEO, it is important to also clarify that SEO does not encompass other online activities that are designed to bring traffic to (or promote) your website.