Googlebot is the search bot software used by Google, which collects documents from the web to build a searchable index for the Google Search engine.
If a webmaster wishes to restrict the information on their site available to a Googlebot, or another well-behaved spider, they can do so with the appropriate directives in a robots.txt file, or by adding the meta tag <meta name="Googlebot" content="nofollow" /> to the web page.