Many companies are told by their marketing company that they should have a blog on their website. Blogs are often used for a number or purposes, some of which are for the visitor and some which are more useful for SEO (search engine optimisation).
With a blog you can add unlimited content to your site that doesn’t clutter up the main navigation, you may want to write about company news or industry news or you may want to start a discussion on a certain topic. The fresh content on your site will help towards the SEO but it needs to be relevant to your business. Also it is a great place to get in a few more keywords. Writing an article about a recent project is a great way to promote your business, make it relevant and useful to the visitor and also get great SEO content on your website.