Permalink are the permanent link to a post or categories in a blog. Let me explain this with an example in this blog. Google Sitemap post permalink is http://blogmines.com/blog/2006/03/01/google-sitemap/. When we want to refer to a post it is always better to have a more meaning full link than having a question mark and a number. For WordPress blogs this needs to be configured under the option section. And you will recieve a waring message when the options are changed in Permalink section. so make sure the permalink’s required plugin has been configured.