What is the purpose of a 'robots.txt' file on a website?

The purpose of a 'robots.txt' file on a website is to instruct web robots, such as search engine crawlers, which parts of the website they are allowed to access and which parts they should not crawl. A 'robots.txt' file is a text file that is placed in the root directory of a website. It uses specific syntax to define rules for web robots, telling them which URLs or directories they are permitted or disallowed from crawling. This is primarily used to manage crawl traffic, prevent search engines from indexing duplicate content, or keep certain areas of a website private. For example, a website might use a robots.txt file to prevent search engines from crawling the administrative backend, the shopping cart pages, or the image directories. This can help to improve the website's search engine optimization (SEO) by ensuring that search engines focus on the most important content and that the website's crawl budget is used efficiently. It is important to note that robots.txt is a guideline, not a mandate. While most reputable search engine crawlers will respect the rules defined in the file, malicious robots or those from less reputable search engines may ignore them. Therefore, robots.txt should not be used as a primary security measure to protect sensitive content.