About /robots.txt

In a nutshell

Web site owners use the /robots.txt file to give instructions about their site to web robots; this is called The Robots Exclusion Protocol.

It works likes this: a robot wants to vists a Web site URL, say http://www.example.com/welcome.html. Before it does so, it firsts checks for http://www.example.com/robots.txt, and finds:

User-agent: *
Disallow: /

The "User-agent: *" means this section applies to all robots. The "Disallow: /" tells the robot that it should not visit any pages on the site.

There are two important considerations when using /robots.txt:

• robots can ignore your /robots.txt. Especially malware robots that scan the web for security vulnerabilities, and email address harvesters used by spammers will pay no attention.
• the /robots.txt file is a publicly available file. Anyone can see what sections of your server you don't want robots to use.

So don't try to use /robots.txt to hide information.

See also:

• Can I block just bad robots?
• Why did this robot ignore my /robots.txt?
• What are the security implications of /robots.txt?