Once upon a time, there was something called “personal homepage” (Links.net) by Justin Hall, created at 1994, considered as the first Blog, it wasn’t called like that until 1997 when Jorn Barger introduced the new term Weblog, this term was created to reflect the process of “logging the web”.
Two years later, at 1999 the term Weblog was shortened to Blog by Petter Merholz. Around these years, several blogging platforms were created to improve the creation of content for these early Blogs. In this process, Evan Williams and Meg Hourihan created Pyra Labs in 1999 (the base of Blogger). Two years later in 2001 the company Six Apart released the first version of Movable Type (Do not forget this name, it was an essential key to the WordPress popularity), a Blog management system.
On the same year (2001) Michel Valdrighi released the first version of b2/cafelog, a blogging system created under the OpenSource license GPL, and stopped giving support to his system around 2003. The same year (2003) Matt Mullenweg, who had an installed version of b2/cafelog, decide to create a fork of this project on SourceForget.net, bringing to life the first release of WordPress!. At the same year, WordPress had a lucky moment when the company Six Apart, decided to change their license and pricing policy to their Movable Type platform; this decision led to a migration of many of the most influential clients of Six Apart to WordPress as an excellent alternative, This situation gave WordPress an unstoppable push to fame as one of the best blogging platforms.
From that moment, and thanks to the 2004 plugins introduction to WordPress, this platform has involved from a blogging system to a complete Content Management System with extended features for almost everything in the web environment.
Right now WordPress is used by several influential companies like TechCrunch, The New Yorker, BBC America, CNN, Forbes, Reuters, Sony, Mashable, on much more. You can check these users at https://wordpress.com/notable-users/
For a more detailed timeline of WordPress go to https://codex.wordpress.org/History.