1. WordPress is free to use,thought it is very much popular: Main reason is that, there are thousands of contributors and volunteers behind building the wordpress , fixing patches, perform bug fixing and suggesting new features. This is one of the reasons WordPress is free to use, it is build by hundreds of WordPress volunteers.
2. There are over 66 million websites build in WordPress and each day there are around 100.000 new website being built using WordPress.Some examples of famous websites build in wordpress are: CNN, Forbes, TechCrunch, Mashable, The New Yorker, BBC America, Variety, Sony Music
3. There are about 73 languages used in wordpess, i.e we can build our website in any langugae like Dutch, Japanese, Swedish and german to French, Hebrew, Spanish and Romanian or Russian.
4. According to the latest numbers there are over 2.700 free themes hosted on WordPress.org.There are now over 34.544 free plugins avaliable.