I've seen a few pages which appear to have been programmed with php but in the URL of the product you don't see any parameters (like ?id=123) and instead there is the product name. Also the file name doesn't end with ".php" but with ".htm" or with nothing at all. I know that they have been programmed with php because the search page ends with ".php". I was wondering how I could do the same for my website as I know it's better for SEO.