The sitemap 0.9 protocol was introduced by www.sitemaps.org and it is the standard that Google and all other major search engines use. Sitemaps are typically XML files and are usually stored in the root folder of the website. They help in extending the accessibility and visibility of your web content by search engines. There are some WordPress Sitemap plugins that you can use to automatically generate sitemaps. you can also go through the Best WordPress Google Maps Plugins.