Googlebot is the web crawler software used by Google, which collects documents from the web to build a searchable index for the Google Search engine. This name is actually the general name for two different types of crawlers: a desktop crawler that simulates a user on a desktop, and a mobile crawler that simulates a user on a mobile device.
When it comes to the technical description, Googlebot operates based on an algorithmic process: automated software (this is the Googlebot) fetches (or “crawls”) pages from the web, indexes those pages, and ranks them in order to present users with the best possible information in response to their search queries. It uses a distributed system of several thousand computers to fetch (or “crawl”) billions of pages on the web. The program that does the fetching is called Googlebot (also known as a robot, bot, or spider).
The crawling process begins with a list of web addresses from past crawls and sitemaps provided by website owners. As Googlebot visits each of these websites, it detects links (SRC and HREF) on each page and adds them to its list of pages to crawl. Determining which sites to crawl, how often, and how many pages to fetch from each site is done by Google’s crawl scheduler. Googlebot can process many types of content, including text, images, video, PDF, and even page elements such as CSS and JavaScript.
Moreover, Googlebot is designed to be distributed on numerous machines to improve performance and scale as the web grows. To avoid overwhelming web servers, or interacting too frequently with sites that change rapidly, Googlebot maintains a “crawl rate limit,” which is the maximum fetching rate for a given site. This crawl rate can be adjusted in Google Search Console by website owners.
Google uses a considerable quantity of technology and data to ensure that the crawling process is efficient. For example, it utilizes a large-scale web graph of 100 million sites and employs machine learning techniques to determine the freshness, relevance, and reliability of web pages. However, to effectively organize content and display the most relevant results to users, Google applies over 200 ranking factors, such as keyword usage, site speed, and mobile-friendliness.
In conclusion, Googlebot is a fundamental part of Google’s search operations—its role in crawling and indexing web content provides the foundation upon which the world’s most widely-used search engine operates.
References:
- Google Search Central. (n.d.). How Google Search Works. [Online] Available at: https://developers.google.com/search/docs/beginner/how-search-works
- Google Search Central. (n.d.). Make your site crawlable. [Online] Available at: https://developers.google.com/search/docs/beginner/seo-starter-guide
- Bifet, A., & Frank, E. (2010). Sentiment knowledge discovery in Twitter streaming data. In Discovery science (pp. 1-15). Springer, Berlin, Heidelberg.
