Joseph Kolb wrote:
In a few words, could someone explain SEF and why it is so important. I understand that it means search engine friendly, but what does it actually do?
On today’s Internet, database driven or dynamic sites are very popular. Unfortunately the easiest way to pass information between your pages is with a query string. In case you don’t know what a query string is, it's a string of information tacked onto the end of a URL after a question mark.
So, what’s the problem with that? Well, most search engines (with a few exceptions - namely Google) will not index any pages that have a question mark or other character (like an ampersand or equals sign) in the URL. So all of those popular dynamic sites out there aren’t being indexed - and what good is a site if no one can find it?
The solution? Search engine friendly URLs. There are a few popular ways to pass information to your pages without the use of a query string, so that search engines will still index those individual pages. I'll cover 3 of these techniques in this article. All 3 work in PHP with Apache on Linux (and while they may work in other scenarios, I cannot confirm that they do).
From
http://www.sitepoint.com/article/search-engine-friendly-urls
Cheers,
Mike