What is a robots.txt file?
A robots.txt file tells search engine crawlers which pages or files the crawler can or can’t request from your site. This is used mainly to avoid overloading your site with requests; it is not a mechanism for keeping a web page out of Google. To keep a web page out of Google, you should use
noindex directives, or password-protect your page.
What is robots.txt used for?
robots.txt is used primarily to manage crawler traffic to your site, and usually to keep a page off Google, depending on the file type:
|Page Type||Traffic management||Hide from Google||Description|
|Web page||For web pages (HTML, PDF, or other non-media formats that Google can read), robots.txt can be used to manage crawling traffic if you think your server will be overwhelmed by requests from Google’s crawler, or to avoid crawling unimportant or similar pages on your site.You should not use robots.txt as a means to hide your web pages from Google Search results. This is because, if other pages point to your page with descriptive text, your page could still be indexed without visiting the page. If you want to block your page from search results, use another method such as password protection or a |
|Media file||Use robots.txt to manage crawl traffic, and also to prevent image, video, and audio files from appearing in Google search results. (Note that this won’t prevent other pages or users from linking to your image/video/audio file.)Read more about preventing images from appearing on Google.Read more about preventing video files from appearing on Google.|
|Resource file||You can use robots.txt to block resource files such as unimportant image, script, or style files, if you think that pages loaded without these resources will not be significantly affected by the loss. However, if the absence of these resources make the page harder for Google’s crawler to understand the page, you should not block them, or else Google won’t do a good job of analyzing pages that depend on those resources.|
Understand the limitations of robots.txt
Before you create or edit robots.txt, you should know the limits of this URL blocking method. At times, you might want to consider other mechanisms to ensure your URLs are not findable on the web.
- Robots.txt directives may not be supported by all search engines
The instructions in
robots.txtfiles cannot enforce crawler behavior to your site, it’s up to the crawler to obey them. While Googlebot and other respectable web crawlers obey the instructions in a
robots.txtfile, other crawlers might not. Therefore, if you want to keep information secure from web crawlers, it’s better to use other blocking methods, such as password-protecting private files on your server.
- Different crawlers interpret syntax differently
Although respectable web crawlers follow the directives in a
robots.txtfile, each crawler might interpret the directives differently. You should know the proper syntax for addressing different web crawlers as some might not understand certain instructions.
- A robotted page can still be indexed if linked to from other sites
While Google won’t crawl or index the content blocked by
robots.txt, we might still find and index a disallowed URL if it is linked from other places on the web. As a result, the URL address and, potentially, other publicly available information such as anchor text in links to the page can still appear in Google search results. To properly prevent your URL from appearing in Google Search results, you should password-protect the files on your server or use the noindex meta tag or response header (or remove the page entirely).