Although it is easily overlooked, the filenames structure you apply to the way you build your website has a significant and direct effect on your SEO performance. Since your filenames structure will is part of your URL, it's important to be specific and to use keywords, because using keywords in your filenames structure is just as important as using keywords in the body of your pages and their content. Consider the following examples:
Let's say your website is a service that focuses on car repairs, and sells spare parts intended for use in car repairs.
www.carrepairs.com/product_1.html
www.carrepairs.com/product_2.html
General filenames structure like this does nothing to help the search engines pick up on the focus of your site or what it offer. However, a simple tweaking to your filenames structure can help amplify your SEO marketing, so that your URL and domain name clearly show what you are selling.
www.carrepairs.com/carbeurator.html
www.carrepairs.com/brake-pads.html
Using keywords in your filenames structure and directory structure in this way will do wonders for search engine optimization of your site. It's also a good idea to use the keyword associated with your filenames structure as the main keyword on the page itself. Also, try to use hyphens instead of underscores when separating words in your filenames structure, and limit them to three or four words at the most.
Do some keyword research too, and try to find keywords with little competition. Then add additional pages to serve your filenames structure with these keywords in order to target your search engine marketing towards low competition niches.
Another reason your filenames structure plays an important role in SEO marketing is because off the importance of links. Inbound links are one of the most important things that search engine crawlers look for, and if they find links with a filenames structure that is rich in keywords, they'll attribute your site with even more relevance.
Dynamic pages can present a problem to your filenames structure, because the complicated URLs they use are often ignored by crawlers. While it can be hard to include keyword rich filenames in dynamic pages, there are ways around this.
But remember, having an effective filenames structure is just one of many SEO tools that lead to success. The best web optimizers will tell you that it is using this filenames structure technique in combination with inbound linking, optimized copy and other methods that will lead to the best results and rankings.