Currently, the world's largest technology company by revenue is currently Apple Inc. Apple was founded in 1976 by Steve Jobs, Steve Wozniak, and Ronald Wayne. The company initially started out as a personal computer manufacturer, but it has since expanded its offerings to include consumer electronics, software, and online services. Some of Apple's most well-known products include the iPhone, iPad, MacBook, and Apple Watch. The company is also responsible for the development and distribution of the MacOS and iOS operating systems.

Another tech giant and worthy of mentioning, is Microsoft, which was founded in 1975 by Bill Gates and Paul Allen. Microsoft is primarily known for its Windows operating system, which is used on the majority of personal computers worldwide. The company also produces a variety of software products, including the Office Suite and the Edge Web Browser, and has a growing presence in the gaming industry through its Xbox console and PC gaming app.

Amazon, founded by Jeff Bezos in 1994, is known for its e-commerce platform, Amazon.com, which is the largest online retailer in the world. The company also offers a wide range of other services, including streaming video and music through Amazon Prime and cloud computing through Amazon Web Services. Amazon has also expanded its reach into other areas, such as grocery delivery with Whole Foods and digital advertising.

Google, Alphabet Inc's subsidiary, formed in 1998, is one of the world's most popular search engines. The company's other products include the Android mobile operating system, the Google Chrome web browser, Google Maps, and the Google Suite of productivity tools. Google has also been heavily investing in AI and machine learning, which is expected to drive the company's future growth.

Lastly, Facebook founded by Mark Zuckerberg in 2004, is the largest social networking platform in the world. The company also owns other popular social media apps and services such as Instagram, WhatsApp and Oculus VR. Additionally, Facebook has been developing its own technology like the Libra cryptocurrency and NPE team, which creates experimental apps and features.

Each of these companies has played a major role in shaping the technology industry as we know it today and are constantly innovating in order to stay ahead of the curve. All of them have their strengths, and all of them dominate in certain areas of the industry. However, they are all considered to be the biggest in the industry, with Apple and Microsoft at the top of the list in terms of revenue.

Please let me know if there is anything else I can help you with.