Sitemaps are designed for webmasters to provide search engines with a list of pages on their websites which are available for crawling and indexing (finding and saving). The most popular sitemap is an XML file that lists pages for a site along with additional metadata about each page (when it was last updated, how often it usually changes, and how important it is, relative to other URLs in the site) so that search engines can more intelligently crawl the site.
Regularly submitting your updated sitemap with Google is highly recommended.
Spiders (website crawling programs) normally discover pages from inbound links (links pointing to you from other sites) and links within your site. Sitemaps replace this method with one that provides more information and can be influenced by the site owner. However, using a sitemap does not guarantee your web pages are included in search engines; rather, it provides information for search engines to efficiently crawl your site.
Once you have an XML sitemap, Google, Yahoo!, and Microsoft will crawl and index your pages, based on their opinions and internal policies. We have no control over when, how quickly, and the time frame it will take the search engines to do this. Most website owners see a change in page ranking within four to six weeks.
How do I create an XML site map?
For a WordPress site, the easiest way is to download the WordPress plugin XML Sitemap Feed and install it in your WordPress plugins folder. Or search for it from within your WordPress Plugins page.
Another way is to enroll with Attracta. You can find this service within your cPanel, or by visiting their homepage.
Otherwise, simply search online for "XML sitemap" and you will find many sitemap generators.