Web creators are always asking whether you should use keywords in the file or directory names or both. This is a great question and one deserving an answer. The rankings will not be affected most often. In fact it may help little in regards to increasing your ranking, but it does serve a purpose. Files and directories help with click through. In other words, people tend to choose the links with the keywords over those that don’t have them.
By putting keywords in the directory or file names, you are helping the chances that your site is the one from results clicked on and then of course sales are made from. The keywords can also be used as anchor text to help you with your links.
The keywords offer a better way for the search engines to crawl through your sites. By offering a better name you get better search results. There is a word of caution here though.
NOTE: You never want to change the URL. By changing the filename and the URL you are changing the location. In this case you will lose consumers. It will also lose the search engine. The only time to change the file name if it has been established previously is by creating a 301 redirect. This at least allows the search engine and consumer to find you. The older the page the better, and the age is somewhat determined by the URL you have. New sites can have the keywords in the file or directory name. If you already have a site then beware of changing the URL. Short URL’s are helpful for keywords as well, but don’t change the filenames once established.