Apart from that, there are certain Govt. and Security sites which do not wish to be listed on Google. And many other small corporate wish the same for their internal sites.
There are certain senarios when some one wont want his/her site to get crawled by any crawler b/c crawlers do consume bandwidth suppose you have a site which is indexed on google and it gets updated regularly! Crawlers would regularly visit your website consume your webserver bandwidth and update the content over there search engine however you might not want them to visit again and again ! in that case it would be of particular importance to not to allow them to access the web again and again !
The Blog of Em 
Why would anyone want NOT to be listed? Anyway, nice tip mooosooo!!!
There are sites like http://www.nu.edu.pk 😉 and many more!
Apart from that, there are certain Govt. and Security sites which do not wish to be listed on Google. And many other small corporate wish the same for their internal sites.
ahaan, but wudnt NU prefer to be on google?
you guys get a room :p
can you use it to stop certain keywords being searched and how?
There are certain senarios when some one wont want his/her site to get crawled by any crawler b/c crawlers do consume bandwidth suppose you have a site which is indexed on google and it gets updated regularly! Crawlers would regularly visit your website consume your webserver bandwidth and update the content over there search engine however you might not want them to visit again and again ! in that case it would be of particular importance to not to allow them to access the web again and again !
Regards
Azeem