By this I am referring to website addresses which contain a lot of code such as <=?> or similar. These crazy lines of code are typically produced by databases and where not considered to be SEO friendly URLS because they had little or no relevance to the content contained within the pages themselves.
Search Engines (at the time) could not read them but also people could not read them either, they seem to be complete jargon to the untrained eye and coupled with the fact that no one would ever remember or recollect them they where something that most of us tried to avoid.
SEO Friendly URLs
If for example your website address was:
It was much more preferable to have:
It is still important to have a clean URL such as the second example. It helps to create relevance to the content and to be honest is much more pleasing to the eye. You can read a good detailed description of clean URLs (or Permalinks) on Wikipedia.
If your using a blog, specifically WordPress its always a good idea to set up your Permalinks correctly as soon as you do a fresh install. The benfits in regards SEO and gaining listings in the SERPS is extreme in combination with a raft of other plugins you can add toaid in creating exposure.