A sitemap is a file where you can list the web pages of your site to tell Google and other Search engines about the organization of your site content. Search engine web crawlers like Googlebot read this file to more intelligently crawl your site. 

Online Sitemap Generator 

 Tool used to create XML sitemap for a given website. Fundamental   parameters of the generation process can be customized by the user.

Free Online XML Sitemap Generator here