The text of the URL or web address is an extra source of important information for the search engine spider. Having your main keywords in the URL for each product and category page can significantly help your search engine rankings. Search Engine Friendly URLs use a server feature called mod_rewrite to re-write the URL so that the outside world sees only the URL generated by the database from the product name and category name information.

From this: http://www.babyben.co.uk/product_info.php?products_id=1026

To this: http://www.babyben.co.uk/bushaby-waterproof-baby-suit-p-1026.html