Why?

WordPress is an online, open source website creation tool written in PHP. It’s probably the easiest and most powerful blogging and website content management system (or CMS) in existence today. WordPress started as just a blogging system, but has evolved to be used as full content management system and so much more through the thousands of plugins, widgets and themes.

Importance?

It is the most versatile content management system (CMS).Wordpress powers 22.5% of all websites on the internet. It is cost-effective and flexible. There are currently 2600+ WordPress themes and 31,000+ plugins available for free. WordPress is a free and open-source content management system (CMS) based on PHP and MySQL. Features include
plugin architecture and a template system. WordPress was used by more than 23.3% of the top 10 million websites as of January 2015 WordPress is the most popular blogging system in use on the Web.