This is done using Googlebot is Google's web crawling bot (sometimes also called a "spider"). Crawling is the process by which Googlebot discovers new and updated pages to be added to the Google index.
Crawling is the process by which Googlebot discovers new and updated pages to be added to the Google index. ... Submit Sitemap to Google Webmaster Tools – The first place you should take your sitemap for a new website is Google Webmaster Tools.