URLs - should you care? And what are SEF URLS?

The easy answer is yes you should care and they should come under the umbrella of SEF (Search Engine Friendly) URLS.  Search Engine Friendly is really a term related to being able to understand what that web page is about without seeing any of the content of the site.

It is common that a URL can be something like www.iamsellingclothes.com/index.php?id=4332e4

What we can understand about the URL above? Well there is a good chance they sell clothes.  What the type of clothes they are selling can not be determined. An SEF URL on this same site may be something like www.iamsellingclothes.com/womens-dresses-green.  As a human we can already understand what the content on that page is with a SEF URL.  The other thing to mention here is that keywords relating to the content of that page are included in the URL sturcture.  In this example

Google webmaster quote that a "site's URL should be as simple as possible.".... and "that URLS are constructed logically and in a manner that is most intelligible to humans (when possible, readble words rahter than long ID numbers)."  Because the Search Bots are so secretive no body knows what the weighting is of an SEF URL, but you have to remember that the algorithms of these Search Bots have been programmed by human beings.

When defining URL stuctures always stick to Keep it Simple Stupid.

If you are interested in URL structure you should read what the webmaster central