The robots.txt file, also known as the robots exclusion protocol or standard, is a text file that website owners create to instruct web robots, typically search engine crawlers, on how to crawl and index pages on their website. The file is placed in the root directory of the website and is one of the primary ways of communicating with web crawlers to manage and control their access to certain areas of the site. It uses a simple set of commands that can allow or disallow access to specific files and directories. When a crawler visits a website, it looks for the robots.txt file first, and if it finds one, it will read the instructions to understand which areas of the site are off-limits. The robots.txt file is publicly accessible and can be viewed by anyone to see what parts of a site the owner prefers not to be indexed. However, it is important to note that not all crawlers follow the instructions in a robots.txt file—malicious bots or crawlers looking for security vulnerabilities might ignore these directives. Moreover, while the robots.txt file can prevent crawling of content, it does not inherently prevent content from being indexed if it is linked from other sites.