robots.txt: For Indexing and Crawling of Search Engines

Although the robots.txt file is a very important file if you want to have a good ranking on search engines, many Web sites don't offer this file.

If your Web site doesn't have a robots.txt file yet, read on to learn how to create one. If you already have a robots.txt file, read our tips to make sure that it doesn't contain errors.

What is robots.txt?

When a search engine crawler comes to your site, it will look for a special file on your site. That file is called robots.txt and it tells the search engine spider, which Web pages of your site should be indexed and which Web pages should be ignored.

The robots.txt file is a simple text file (no HTML), that must be placed in your root directory, for example:

http://www.yourwebsite.com/robots.txt

How do I create a robots.txt file?

As mentioned above, the robots.txt file is a simple text file. Open a simple text editor to create it. The content of a robots.txt file consists of so-called "records".

A record contains the information for a special search engine. Each record consists of two fields: the user agent line and one or more Disallow lines. Here's an example:

User-agent: googlebot
Disallow: /cgi-bin/

This robots.txt file would allow the "googlebot", which is the search engine spider of Google, to retrieve every page from your site except for files from the "cgi-bin" directory. All files in the "cgi-bin" directory will be
ignored by googlebot.

The Disallow command works like a wildcard. If you enter

User-agent: googlebot
Disallow: /support

both "/support-desk/index.html" and "/support/index.html" as well as all other files in the "support" directory would not be indexed by search engines.

If you leave the Disallow line blank, you're telling the search engine that all files may be indexed. In any case, you must enter a Disallow line for every User-agent record.

If you want to give all search engine spiders the same rights, use the following robots.txt content:

User-agent: *
Disallow: /cgi-bin/

Where can I find user agent names?

You can find user agent names in your log files by checking for requests to robots.txt. Most often, all search engine spiders should be given the same rights. in that case, use "User-agent: *" as mentioned above.

Things you should avoid

If you don't format your robots.txt file properly, some or all files of your Web site might not get indexed by search engines. To avoid this, do the following:

1. Don't use comments in the robots.txt file
   
   Although comments are allowed in a robots.txt file, they might confuse some search engine spiders.
   
   "Disallow: support # Don't index the support directory" might be misinterepreted as "Disallow: support#Don't index the support directory".
   
   
   
2. Don't use white space at the beginning of a line. For example, don't write
   
   placeholder User-agent: *
   place Disallow: /support
   
   but
   
   User-agent: *
   Disallow: /support
   
   
   
3. Don't change the order of the commands. If your robots.txt file should work, don't mix it up. Don't write
   
   Disallow: /support
   User-agent: *
   
   but
   
   User-agent: *
   Disallow: /support
   
   
   
4. Don't use more than one directory in a Disallow line. Do not use the following
   
   User-agent: *
   Disallow: /support /cgi-bin/ /images/
   
   Search engine spiders cannot understand that format. The correct syntax for this is
   
   User-agent: *
   Disallow: /support
   Disallow: /cgi-bin/
   Disallow: /images/
   
   
   
5. Be sure to use the right case. The file names on your server are case sensitve. If the name of your directory is "Support", don't write "support" in the robots.txt file.
   
   
   
6. Don't list all files. If you want a search engine spider to ignore all files in a special directory, you don't have to list all files. For example:
   
   User-agent: *
   Disallow: /support/orders.html
   Disallow: /support/technical.html
   Disallow: /support/helpdesk.html
   Disallow: /support/index.html
   
   You can replace this with
   
   User-agent: *
   Disallow: /support
   
   
   
7. There is no "Allow" command
   
   Don't use an "Allow" command in your robots.txt file. Only mention files and directories that you don't want to be indexed. All other files will be indexed automatically if they are linked on your site.
   
   

Tips and tricks:

1. How to allow all search engine spiders to index all files

Use the following content for your robots.txt file if you want to allow all search engine spiders to index all files of your Web site:
User-agent: *
Disallow:

2. How to disallow all spiders to index any file

If you don't want search engines to index any file of your Web site, use the following:
User-agent: *
Disallow: /

3. Where to find more complex examples.

If you want to see more complex examples, of robots.txt files, view the robots.txt files of big Web sites:

• http://www.cnn.com/robots.txt
• http://www.nytimes.com/robots.txt
• http://www.spiegel.com/robots.txt
• http://www.ebay.com/robots.txt

Your Web site should have a proper robots.txt file if you want to have good rankings on search engines. Only if search engines know what to do with your pages, they can give you a good ranking.