Since it began in 2003, WordPress has grown to be the largest self-hosted blogging tool in the world since its beginning in 2003. WordPress is used on millions of sites and seen by tens of millions of people every day.
WordPress started as a platform / system just for blogging, but has evolved into a full content management system and so much more through the thousands of themes, plugins and widgets available.
On WordPress.Org you can download and install the WordPress software. You need a web host and some time – or you hire someone like me. There is also a service called WordPress.Com which lets you get started with a new and free WordPress-based blog in minutes, but varies in several ways and is less flexible than the WordPress you download and install yourself.