View source for Robots Exclusion Standard

The '''robots exclusion standard''' or '''robots.txt protocol''' is a convention to prevent cooperating [[web spider]]s and other [[web robot]]s from accessing all or part of a [[website]]. The information specifying the parts that should not be accessed is specified in a file called '''robots.txt''' in the top-level directory of the website.

The robots.txt patterns are matched by simple substring comparisons, so care should be taken to make sure that patterns matching directories have the final '/' character appended: otherwise all files with names starting with that substring will match, rather than just those in the directory intended.

==Examples==
This example '''allows all robots''' to visit '''all files''' because the wildcard "*" specifies all robots. 
 User-agent: *
 Disallow:

This example keeps '''all robots out''':
 User-agent: *
 Disallow: /

The next is an example that tells '''all crawlers''' not to enter into four directories of a website:
 User-agent: *
 Disallow: /cgi-bin/
 Disallow: /images/
 Disallow: /tmp/
 Disallow: /private/

Example that tells '''a specific crawler''' not to enter one specific directory:
 User-agent: BadBot
 Disallow: /private/

Example demonstrating how comments can be used:
 # Comments appear after the "#" symbol at the start of a line, or after a directive
 User-agent: * # match all bots
 Disallow: / # keep them out

===Compatibility===

In order to prevent access to all pages by robots,

 Disallow: *

is not appropriate as this is not a stable standard extension. For example, despite the fact that Google claims support for this tag<ref>http://www.google.com/webmasters/remove.html</ref>, it in fact does not<ref>http://groups.google.com/groups?q=elvey+googlebot</ref>.

Instead:
 Disallow: /
should be used.

==Alternatives==
robots.txt is older and more widely accepted, but there are other methods (which can be used together with robots.txt) that allow greater control, like disabling indexing of images only or disabling archiving of page contents.

===HTML meta tags for robots===
[[HTML]] [[meta tag]]s can be used to exclude robots according to the contents of web pages. Again, this is purely advisory, and also relies on the cooperation of the robot programs. For example, 

<pre><meta name="robots" content="noindex,nofollow" /></pre>

within the <code>HEAD</code> section of an [[HTML]] document tells search engines such as [[Google]], [[Yahoo!]], or [[MSN]] to exclude the page from its index and not to follow any links on this page for further possible indexing.

(See [http://www.robotstxt.org/wc/meta-user.html HTML Author's Guide to the Robots META tag].)

=== Directives within a page===
The <tt><NOINDEX></tt> tag is a non-standard HTML tag whose intent is to indicate portions of a page that should not be indexed, such as common navigation or footer.  Using it without a namespace will make [[XHTML]] pages invalid.

Google uses comments for the same purpose: <tt><nowiki><!--googleoff: index--> ... <!--googleon: index--></nowiki></tt>

== See also ==
* [[.htaccess]]
* [[Rewrite engine|mod_rewrite]]
* [[Web crawler]]
* [[Spam in blogs#rel=nofollow|The nofollow attribute]]

==References==
<references />
==External links==
*[http://www.fleiner.com/bots/ How to keep bad robots, spiders and web crawlers away]
*[http://www.kloth.net/internet/badbots.php List of Bad Bots]: A short list of bad spiders and nasty bots seen on my different web sites
*[http://laffey.tv/favicon_error_logs.html HOWTO: Serving up default favicon.ico and robots.txt files with Apache]
*[http://tool.motoricerca.info/robots-checker.phtml Robots.txt Checker] (validates robots.txt files and gives optimization tips)
*[http://www.robotstxt.org/wc/norobots.html A Standard for Robot Exclusion]
*[http://www.robotstxt.org/wc/exclusion.html Robots Exclusion]
*[http://www.yellowpipe.com/yis/tools/robots.txt/ Robots.txt Online Generator]
*[http://www.theinquirer.net/?article=19357 White House site has oddities, like Bush site], Nick Farrell (29 October 2004)
*[http://www.cre8asiteforums.com/forums/index.php?showtopic=8412&hl= Comprehensive Robots.txt Tutorial]
*[http://www.servergrade.com.au/faq/answers/robots-text.html Using Robots.txt To Manage Search Engine Spiders]

===Examples===
*[http://www.askapache.com/seo/seo-with-robotstxt.html SEO with Robots.txt] &mdash; by AskApache

[[Category:World Wide Web]]