Introduction To "robots.txt" [all about robots.txt]

Hello guys this is Prabh jeet hope you all are enjoying good health. 
So In this Short Introduction What u will learn .

• What is robots.txt ? 
• The importance of robots.txt .
• How do I create a robots.txt file ? 
• Where can I find user agent names ? 
• and some interesting things .

The importance of robots.txt


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:
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".


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


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
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/


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.


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


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.