WordPress started as just a blogging system, but has since evolved into a full content management system and more through plugins, widgets, and themes, WordPress is limited only by our imagination.
WordPress is Open Source software so there is no running cost. It is built on PHP/MySQL and is licensed under GPL.
WordPress is easy to use on your website. The administration section is easy to use, so it is simple to add articles/content to your site.
WordPress software follows all the Web Standards and keeps your website compliant to all the rules that have to be followed when running a site.
Search Engines have to be kept in mind when building a website. WordPress uses functions which allow it to be search engine friendly. For example making categories, give your pages sensible names and the use of header tags.