A spider (also called a web crawler or bot) is an automated program that browses the internet to index web pages. These programs are often used by search engines like Google, Bing, or Yahoo to discover and update content in their search index.
Starting Point: The spider begins with a list of URLs to crawl.
Analysis: It fetches the HTML code of a webpage and analyzes its content, links, and metadata.
Following Links: It follows the links found on the page to discover new pages.
Storage: The collected data is sent to the search engine’s database for indexing.
Repetition: The process is repeated regularly to keep the index up to date.
Search engine optimization (SEO)
Price comparison websites
Web archiving (e.g., Wayback Machine)
Automated content analysis for AI models
Some websites use a robots.txt file to specify which areas can or cannot be crawled by a spider.