Search Engine optimization is one of the key factor for your site. If you spend millions of dollars on making your website looks good and bug free then also its possible that you will not get attention of search engine because of your URLs. For example you’re having shopping cart created in asp.net and you have not optimized your URL then it will look like following. www.foo.com ?Product.aspx?Category=1& Page=1 If you search engine read this URL then search engine will not know much about this URLs. Even normal people who does not know querystring menaing(?Category=watch&Page=1). But you have URL like following. www.foo.com/prduct/category/watch/page/1 It’s easy to read and search engine and normal people will know that you are loading products that belongs to category watch and this is a first page.