robots
   HOME

TheInfoList



OR:

" \n\n\n\n\n\n\nrobots.txt is the
filename<\/a> \n\n\n\n\nA filename or file name is a name used to uniquely identify a computer file in a file system. Different file systems impose different restrictions on filename lengths.\n\nA filename may (depending on the file system) include:\n* name – base ...
<\/span><\/div> used for implementing the Robots Exclusion Protocol, a standard used by
website<\/a> \n\n\n\n\nA website (also written as a web site) is any web page whose content is identified by a common domain name and is published on at least one web server. Websites are typically dedicated to a particular topic or purpose, such as news, educatio ...
<\/span><\/div>s to indicate to visiting
web crawler<\/a> \n\n\n\n\nWeb crawler, sometimes called a spider or spiderbot and often shortened to crawler, is an Internet bot that systematically browses the World Wide Web and that is typically operated by search engines for the purpose of Web indexing (''web spider ...
<\/span><\/div>s and other
web robots<\/a> which portions of the website they are allowed to visit.\n\nThe standard, developed in 1994, relies on
voluntary compliance<\/a> Voluntary compliance is conforming (\" complying\") to a rule, without facing negative consequences if not complying.\n In corporations \nVoluntary compliance is one of possible ways of practicing corporate social responsibility. It is seen as an alte ...
<\/span><\/div>. Malicious bots can use the file as a directory of which pages to visit, though standards bodies discourage countering this with
security through obscurity<\/a>. Some archival sites ignore robots.txt. The standard was used in the 1990s to mitigate server<\/a> overload. In the 2020s, websites began denying bots that collect information for
generative artificial intelligence<\/a> \n\n\n\n\n\n\nGenerative artificial intelligence (Generative AI, GenAI, or GAI) is a subfield of artificial intelligence that uses generative models to produce text, images, videos, or other forms of data. These models Machine learning, learn the underlyin ...
<\/span><\/div>.\n\nThe \"robots.txt\" file can be used in conjunction with
sitemaps<\/a>, another robot inclusion standard for websites.\n


History<\/h1><\/p>\nThe standard was proposed by Martijn Koster<\/a>, when working for Nexor<\/a><\/ref> in February 1994 on the ''www-talk'' mailing list, the main communication channel for WWW-related activities at the time. Charles Stross<\/a> claims to have provoked Koster to suggest robots.txt, after he wrote a badly behaved web crawler that inadvertently caused a

denial-of-service attack<\/a> \n\n\n\n\n\n\n\nIn computing, a denial-of-service attack (DoS attack) is a cyberattack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host co ...
<\/span><\/div> on Koster's server.\n\nThe standard, initially RobotsNotWanted.txt, allowed
web developer<\/a> \n\n\n\nA web developer is a programmer who develops World Wide Web applications using a client\u2013server model. The applications typically use HTML, CSS, and JavaScript in the client, and any general-purpose programming language in the server. is used ...
<\/span><\/div>s to specify which bots should not access their website or which pages bots should not access. The internet was small enough in 1994 to maintain a complete list of all bots;
server<\/a> overload was a primary concern. By June 1994 it had become a ''de facto'' standard<\/a>;<\/ref> most complied, including those operated by search engines such as
WebCrawler<\/a> \n\n\n\n\n\nWebCrawler is a search engine, and one of the oldest surviving search engines on the web today. For many years, it operated as a metasearch engine. WebCrawler was the first web search engine to provide full text search.\n History\n\nBrian Pinker ...
<\/span><\/div>,
Lycos<\/a> \n\n\nLycos, Inc. (stylized as LYCOS), is a web search engine and web portal established in 1994, spun out of Carnegie Mellon University. Lycos also encompasses a network of email, web hosting, social networking, and entertainment websites. The company ...
<\/span><\/div>, and
AltaVista<\/a> \n\n\n\nAltaVista was a web search engine established in 1995. It became one of the most-used early search engines, but lost ground to Google and was purchased by Yahoo! in 2003, which retained the brand, but based all AltaVista searches on its own sear ...
<\/span><\/div>.<\/ref>\n\nOn July 1, 2019, Google announced the proposal of the Robots Exclusion Protocol as an official standard under
Internet Engineering Task Force<\/a> \n\n\n\n\n\n\n\n\nThe Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP\/IP). It has no formal membership roster ...
<\/span><\/div>. A proposed standard was published in September 2022 as RFC 9309.\n


Standard<\/h1><\/p>\nWhen a site owner wishes to give instructions to web robots they place a text file called in the root of the web site hierarchy (e.g. ). This text file contains the instructions in a specific format (see examples below). Robots that choose to follow the instructions try to fetch this file and read the instructions before fetching any other file from the

website<\/a> \n\n\n\n\nA website (also written as a web site) is any web page whose content is identified by a common domain name and is published on at least one web server. Websites are typically dedicated to a particular topic or purpose, such as news, educatio ...
<\/span><\/div>. If this file does not exist, web robots assume that the website owner does not wish to place any limitations on crawling the entire site.\n\nA robots.txt file contains instructions for bots indicating which web pages they can and cannot access. Robots.txt files are particularly important for web crawlers from search engines such as Google.\n\nA robots.txt file on a website will function as a request that specified robots ignore specified files or directories when crawling a site. This might be, for example, out of a preference for privacy from search engine results, or the belief that the content of the selected directories might be misleading or irrelevant to the categorization of the site as a whole, or out of a desire that an application only operates on certain data. Links to pages listed in robots.txt can still appear in search results if they are linked to from a page that is crawled.\n\nA robots.txt file covers one
origin<\/a>. For websites with multiple subdomain<\/a>s, each subdomain must have its own robots.txt file. If had a robots.txt file but did not, the rules that would apply for would not apply to . In addition, each URI scheme<\/a> and
port<\/a> \n\n\nA port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...
<\/span><\/div> needs its own robots.txt file; does not apply to pages under or .\n


Compliance<\/h1><\/p>\nThe robots.txt protocol is widely complied with by bot operators. \n


Search engines<\/h2><\/p>\nSome major

search engines<\/a> \n\n\nSearch engines, including web search engines, selection-based search engines, metasearch engines, desktop search tools, and web portals and vertical market websites have a search facility for online databases.\n\n\n\n\n\n\n By content\/topic \n Gene ...
<\/span><\/div> following this standard include Ask,<\/ref> AOL,<\/ref> Baidu,<\/ref> Bing,<\/ref> DuckDuckGo,<\/ref> Kagi,<\/ref> Google,<\/ref> Yahoo!,<\/ref> and Yandex.<\/ref>\n


Archival sites<\/h2><\/p>\nSome web archiving projects ignore robots.txt. Archive Team<\/a> uses the file to discover more links, such as sitemap<\/a>s. Co-founder Jason Scott<\/a> said that \"unchecked, and left alone, the robots.txt file ensures no mirroring or reference for items that may have general use and meaning beyond the website's context.\" In 2017, the

Internet Archive<\/a> \n\n\n\n\n\n\n\n\n\nThe Internet Archive is an American 501(c)(3) organization, non-profit organization founded in 1996 by Brewster Kahle that runs a digital library website, archive.org. It provides free access to collections of digitized media including web ...
<\/span><\/div> announced that it would stop complying with robots.txt directives. According to ''
Digital Trends<\/a>'', this followed widespread use of robots.txt to remove historical sites from search engine results, and contrasted with the nonprofit's aim to archive \"snapshots\" of the internet as it previously existed.<\/ref>\n


Artificial intelligence<\/h2><\/p>\nStarting in the 2020s, web operators began using robots.txt to deny access to bots collecting training data for generative AI<\/a>. In 2023, Originality.AI found that 306 of the thousand most-visited websites blocked OpenAI<\/a>'s GPTBot in their robots.txt file and 85 blocked

Google<\/a> \n\n\n\n\n\n\n\nGoogle LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...
<\/span><\/div>'s Google-Extended. Many robots.txt files named GPTBot as the only bot explicitly disallowed on all pages. Denying access to GPTBot was common among news websites such as the
BBC<\/a> \n\n\n\n\n\n\n\nThe British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...
<\/span><\/div> and ''
The New York Times<\/a> \n\n\n\n\n\n\n\n\n\n\n\n''The New York Times'' (''NYT'') is an American daily newspaper based in New York City. ''The New York Times'' covers domestic, national, and international news, and publishes opinion pieces, investigative reports, and reviews. As one of ...
<\/span><\/div>''. In 2023, blog host
Medium<\/a> announced it would deny access to all artificial intelligence web crawlers as \"AI companies have leached value from writers in order to spam Internet readers\".\n\nGPTBot complies with the robots.txt standard and gives advice to web operators about how to disallow it, but ''
The Verge<\/a> \n\n\n\n\n\n''The Verge'' is an American Technology journalism, technology news website headquarters, headquartered in Lower Manhattan, New York City and operated by Vox Media. The website publishes news, feature stories, guidebooks, product reviews, cons ...
<\/span><\/div>''s David Pierce said this only began after \"training the underlying models that made it so powerful\". Also, some bots are used both for search engines and artificial intelligence, and it may be impossible to block only one of these options. ''
404 Media<\/a> \n\n\n''404 Media'' is an online publication that focuses on technology and internet reporting. It covers topics such as hacking, sex work, niche online communities, and the right-to-repair movement. It is worker-owned by its reporters.\n History\n\n' ...
<\/span><\/div>'' reported that companies like
Anthropic<\/a> and Perplexity.ai<\/a> circumvented robots.txt by renaming or spinning up new scrapers to replace the ones that appeared on popular blocklist<\/a>s.\n


Security<\/h1><\/p>\nDespite the use of the terms ''allow'' and ''disallow'', the protocol is purely advisory and relies on the compliance of the web robot<\/a>; it cannot enforce any of what is stated in the file. Malicious web robots are unlikely to honor robots.txt; some may even use the robots.txt as a guide to find disallowed links and go straight to them. While this is sometimes claimed to be a security risk, this sort of '' security through obscurity<\/a>'' is discouraged by standards bodies. The

National Institute of Standards and Technology<\/a> \n\n\n\n\nThe National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into Outline of p ...
<\/span><\/div> (NIST) in the United States specifically recommends against this practice: \"System security should not depend on the secrecy of the implementation or its components.\" In the context of robots.txt files, security through obscurity is not recommended as a security technique.\n


Alternatives<\/h1><\/p>\nMany robots also pass a special user-agent<\/a> to the web server when fetching content. A web administrator could also configure the server to automatically return failure (or pass alternative content<\/a>) when it detects a connection using one of the robots.\n\nSome sites, such as

Google<\/a> \n\n\n\n\n\n\n\nGoogle LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...
<\/span><\/div>, host a humans.txt<\/code> file that displays information meant for humans to read. Some sites such as
GitHub<\/a> \n\n\n\n\nGitHub () is a Proprietary software, proprietary developer platform that allows developers to create, store, manage, and share their code. It uses Git to provide distributed version control and GitHub itself provides access control, bug trackin ...
<\/span><\/div> redirect humans.txt to an ''About'' page.\n\nPreviously, Google had a joke file hosted at \/killer-robots.txt<\/code> instructing
the Terminator<\/a> \n\n\n\n\n\n\n''The Terminator'' is a 1984 American science fiction action film directed by James Cameron, written by Cameron and Gale Anne Hurd and produced by Hurd. It stars Arnold Schwarzenegger as the Terminator, a cybernetic assassin sent back in t ...
<\/span><\/div> not to kill the company founders
Larry Page<\/a> \n\n\n\n\n\n\nLawrence Edward Page (born March 26, 1973) is an American businessman, computer engineer and computer scientist best known for co-founding Google with Sergey Brin.\n\nPage was chief executive officer of Google from 1997 until August 2001 when ...
<\/span><\/div> and
Sergey Brin<\/a>.\n


Examples<\/h1><\/p>\nThis example tells all robots that they can visit all files because the wildcard *<\/code> stands for all robots and the Disallow<\/code> directive has no value, meaning no pages are disallowed. Search engine giant Google open-sourced their robots.txt parser, and recommends testing and validating rules on the robots.txt file using community-built testers such as Tame the Bots and Real Robots Txt. \n\n

\nUser-agent: *\nDisallow: \n<\/pre>\n\nThis example has the same effect, allowing all files rather than prohibiting none.\n\n
\nUser-agent: *\nAllow: \/\n<\/pre>\n\nThe same result can be accomplished with an empty or missing robots.txt file.\n\nThis example tells all robots to stay out of a website:\n\n
\nUser-agent: *\nDisallow: \/\n<\/pre>\n\nThis example tells all robots not to enter three directories:\n\n
\nUser-agent: *\nDisallow: \/cgi-bin\/\nDisallow: \/tmp\/\nDisallow: \/junk\/\n<\/pre>\n\nThis example tells all robots to stay away from one specific file:\n\n
\nUser-agent: *\nDisallow: \/directory\/file.html\n<\/pre>\n\nAll other files in the specified directory will be processed.\n\n\nThis example tells one specific robot to stay out of a website:\n\n
\nUser-agent: BadBot # replace 'BadBot' with the actual user-agent of the bot\nDisallow: \/\n<\/pre>\n\nThis example tells two specific robots not to enter one specific directory:\n\n
\nUser-agent: BadBot # replace 'BadBot' with the actual user-agent of the bot\nUser-agent: Googlebot\nDisallow: \/private\/\n<\/pre>\n\nExample demonstrating how comments can be used:\n\n
\n# Comments appear after the \"#\" symbol at the start of a line, or after a directive\nUser-agent: * # match all bots\nDisallow: \/ # keep them out\n<\/pre>\n\nIt is also possible to list multiple robots with their own rules. The actual robot string is defined by the crawler. A few robot operators, such as 
Google<\/a> \n\n\n\n\n\n\n\nGoogle LLC (, ) is an American multinational corporation and technology company focusing on online advertising, search engine technology, cloud computing, computer software, quantum computing, e-commerce, consumer electronics, and artificial ...
<\/span><\/div>, support several user-agent strings that allow the operator to deny access to a subset of their services by using specific user-agent strings.\n\nExample demonstrating multiple user-agents:\n\n
\nUser-agent: googlebot        # all Google services\nDisallow: \/private\/          # disallow this directory\n\nUser-agent: googlebot-news   # only the news service\nDisallow: \/                  # disallow everything\n\nUser-agent: *                # any robot\nDisallow: \/something\/        # disallow this directory\n<\/pre>\n


The use of the wildcard * in rules <\/h2><\/p>\nThe directive Disallow: \/something\/<\/code> blocks all files and subdirectories starting with \/something\/<\/code>.\n\nIn contrast using a wildcard, (if supported by the crawler), allows for more complex patterns in specifying paths and files to allow or disallow from crawling, for example Disallow: \/something\/*\/other<\/code> blocks URLs such as:\n

\/something\/foo\/other\n\/something\/bar\/other\n<\/pre>\n\nIt would not prevent the crawling of \/something\/foo\/else<\/code>, as that would not match the pattern.\n\nThe wildcard *<\/code> allows greater flexibility but may not be recognized by all crawlers, although it is part of the Robots Exclusion Protocol RFC \n\nA wildcard at the end of a rule in effect does nothing, as that is the standard behaviour.\n


Nonstandard extensions<\/h1><\/p>\n


Crawl-delay directive<\/h2><\/p>\nThe crawl-delay value is supported by some crawlers to throttle their visits to the host. Since this value is not part of the standard, its interpretation is dependent on the crawler reading it. It is used when the multiple burst of visits from bots is slowing down the host. Yandex interprets the value as the number of seconds to wait between subsequent visits. Bing defines crawl-delay as the size of a time window (from 1 to 30 seconds) during which BingBot will access a web site only once.<\/ref> Google ignores this directive, but provides an interface in its search console<\/a> for webmasters, to control the

Googlebot<\/a> \n\n\n\nGooglebot is the web crawler software used by Google that collects documents from the web to build a searchable index for the Google Search engine. This name is actually used to refer to two different types of web crawlers: a desktop crawler (to ...
<\/span><\/div>'s subsequent visits.\n\n
\nUser-agent: bingbot\nAllow: \/\nCrawl-delay: 10\n<\/pre>\n


Sitemap<\/h2><\/p>\nSome crawlers support a Sitemap<\/code> directive, allowing multiple Sitemaps<\/a> in the same robots.txt<\/samp> in the form Sitemap: ''full-url''<\/code>:\n

Sitemap: http:\/\/www.example.com\/sitemap.xml<\/pre>\n


Universal \"*\" match<\/h2><\/p>\nThe ''Robot Exclusion Standard'' does not mention the \"*\" character in the Disallow:<\/code> statement.\n


Meta tags and headers<\/h1><\/p>\nIn addition to root-level robots.txt files, robots exclusion directives can be applied at a more granular level through the use of Robots meta tag<\/a>s and X-Robots-Tag HTTP headers. The robots meta tag cannot be used for non-HTML files such as images, text files, or PDF documents. On the other hand, the X-Robots-Tag can be added to non-HTML files by using .htaccess<\/a> and
<\/a>
files.<\/ref>\n


A \"noindex\" meta tag<\/h2><\/p>\n\n\n<\/syntaxhighlight>\n


A \"noindex\" HTTP response header<\/h2><\/p>\n\nX-Robots-Tag: noindex\n<\/syntaxhighlight>\n\nThe X-Robots-Tag is only effective after the page has been requested and the server responds, and the robots meta tag is only effective after the page has loaded, whereas robots.txt is effective before the page is requested. Thus if a page is excluded by a robots.txt file, any robots meta tags or X-Robots-Tag headers are effectively ignored because the robot will not see them in the first place.\n


Maximum size of a robots.txt file<\/h2><\/p>\nThe Robots Exclusion Protocol requires crawlers to parse at least 500 kibibytes (512000 bytes) of robots.txt files, which Google maintains as a 500 kibibyte file size restriction for robots.txt files.<\/ref>\n


See also<\/h1><\/p>\n\n\n* ads.txt<\/a><\/code>, a standard for listing authorized ad sellers\n* security.txt<\/a><\/code>, a file to describe the process for security researchers to follow in order to report security vulnerabilities\n* eBay v. Bidder's Edge<\/a>\n* Automated Content Access Protocol<\/a> \u2013 A failed proposal to extend robots.txt\n* BotSeer<\/a> \u2013 Now inactive search engine for robots.txt files\n* Distributed web crawling<\/a>\n* Focused crawler<\/a>\n*

Internet Archive<\/a> \n\n\n\n\n\n\n\n\n\nThe Internet Archive is an American 501(c)(3) organization, non-profit organization founded in 1996 by Brewster Kahle that runs a digital library website, archive.org. It provides free access to collections of digitized media including web ...
<\/span><\/div>\n*
Meta elements<\/a> for search engines\n*