What Is Googlebot | Google Search Central  |  Documentation  |  Google for Developers (original) (raw)

Googlebot is the generic name for two types ofweb crawlers used by Google Search:

You can identify the subtype of Googlebot by looking at theHTTP user-agent request header in the request. However, both crawler types obey the same product token (user agent token) in robots.txt, and so you cannot selectively target either Googlebot Smartphone or Googlebot Desktop using robots.txt.

For most sites Google Search primarilyindexes the mobile version of the content. As such the majority of Googlebot crawl requests will be made using the mobile crawler, and a minority using the desktop crawler.

How Googlebot accesses your site

For most sites, Googlebot shouldn't access your site more than once every few seconds on average. However, due to delays it's possible that the rate will appear to be slightly higher over short periods. If your site is having trouble keeping up with Google's crawling requests, you can reduce the crawl rate.

When crawling for Google Search, Googlebot crawls the first 2MB of asupported file type, and the first 64MB of a PDF file. From a rendering perspective, each resource referenced in the HTML (such as CSS and JavaScript) is fetched separately, and each resource fetch is bound by the same file size limit that applies to other files (except PDF files).
Once the cutoff limit is reached, Googlebot stops the fetch and only sends the already downloaded part of the file for indexing consideration. The file size limit is applied on the uncompressed data. Other Google crawlers, for example Googlebot Video and Googlebot Image, may havedifferent limits.

When crawling from IP addresses in the US, the timezone of Googlebot isPacific Time.

Othertechnical properties of Googlebot are described in the overview of Google's crawlers.

Blocking Googlebot from visiting your site

Googlebot discovers new URLs to crawl primarily from links embedded in previously crawled pages. It's almost impossible to keep a site secret by not publishing links to it. For example, as soon as someone clicks a link from your "secret" site to another site, your "secret" site URL may appear in the referrer tag and can be stored and published by the other site in its referrer log.

If you want to prevent Googlebot from crawling content on your site, you have anumber of options. Remember there's a difference between crawling and indexing; blocking Googlebot from crawling a page doesn't prevent the URL of the page from appearing in search results:

Blocking Googlebot affects Google Search (including Discover and all Google Search features), as well as other products such as Google Images, Google Video, and Google News.

Verifying Googlebot

Before you decide to block Googlebot, be aware that the HTTP user-agent request header used by Googlebot is often spoofed by other crawlers. It's important to verify that a problematic request actually comes from Google. The best way to verify that a request actually comes from Googlebot is touse a reverse DNS lookup on the source IP of the request, or to match the source IP against theGooglebot IP ranges.