Generate effective robots.txt files that help ensure Google and other search engines are crawling and indexing your site properly.
The robots exclusion standard, also known as the robots exclusion protocol or simply robots.txt, is a standard used by websites to communicate with web crawlers and other web robots. The standard specifies how to inform the web robot about which areas of the website should not be processed or scanned.
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:
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.