Google LLC is an American multinational technology company that focuses on artificial intelligence, search engine technology, online advertising, cloud computing, computer software, quantum computing, e-commerce, and consumer electronics. 

Facebook is a social networking site that makes it easy for you to connect and share with family and friends online. Originally designed for college students, Facebook was created in 2004 by Mark Zuckerberg while he was enrolled at Harvard University. By 2006, anyone over the age of 13 with a valid email address could join Facebook. Today, Facebook is the world's largest social network, with more than 1 billion users worldwide.

Twitter is an microblogging and social networking service on which users post and interact with messages known as "tweets", 

Instagram is an American photo and video sharing social networking service founded in 2010 by Kevin Systrom and Mike Krieger, and later acquired by Facebook Inc. The app allows users to upload media that can be edited with filters and organized by hashtags and geographical tagging.

Wikipedia is a multilingual free online encyclopedia written and maintained by a community of volunteers through open collaboration and a wiki-based editing system. Individual contributors, also called editors, are known as Wikipedians. Wikipedia is the largest and most-read reference work in history. 

Yandex is a Russian tech company known for creating its Yandex search engine. Yandex is the second largest search engine in Russia. ‍

Yandex had a 39.6% market share in Russia compared to Google’s 57.9% in July 2020. 

Yandex is the biggest technology company in Russia and offers many different types of services and products.

They are known for owning the biggest Russian search engine, but they are also involved in many other things related to technology and the internet.

Yahoo! is an Internet portal that incorporates a search engine and a directory of World Wide Web sites organized in a hierarchy of topic categories. As a directory, it provides both new and seasoned Web users the reassurance of a structured view of hundreds of thousands of Web sites and millions of Web pages.

WhatsApp is a free, multiplatform messaging app that lets you make video and voice calls, send text messages, and more — all with just a Wi-Fi connection. With over 2 billion active users, WhatsApp is especially popular among friends and family who live in different countries and want to stay in touch.