The general idea behind “Google Hacking” is to use special search operators in Google in order to narrow down our search results and find very specific files, usually with a known format. You can find basic usage information here: http://www.google.com/help/basics.html
Advanced Google Operators
A list of Google operators can be found at http://www.google.com/help/operators.html. Using these operators we can search for specific information which might be of value to us during a pen test.
The site: operator restricts the results to websites in a given domain. Let's look at an example:
Notice how all the results come from the target site, hackblitz.blogspot.com. All in all, Google offers 41 hits for this site, which suggests that the website itself is small and has few public pages.
Let's try the filetype operator
This search will show us all the PDF files in the facebook.com site. There are literally hundreds (if not thousands) of interesting searches that can be made, and most of them are listed in Johnny's website: http://johnny.ihackstuff.com . Irrespective of all these google can be used to bypass several paywall and unblock websites that are being blocked by your ISP .Google hacking is also referred as Google Dork .you can find several commands that contains juicy information at Exploit-db website.This is a Simple Google dork command that reveals several facebook username and password :- filetype:txt intext:@gmail.com intext:Facebook intext:password
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