Why is it important?
Choosing a Content Management System (CMS) is probably the most important decision when you build your website. There are a number of CMSs, including open source, license or proprietary systems. As you probably already discovered, most of the suppliers claim that their systems are Search Engine Optimisation (SEO) friendly. Unfortunately, very often the decision makers have a limited knowledge of SEO and would probably have difficulties validating their SEO friendliness.
First of all it might be worthwhile defining what we mean by CMS or more completely, a Content Management System. For the purposes of this entry we will limit ourselves to website systems, so in that arena, a CMS is a web application used to manage the content of a website.