StartUp To Learn Hacking: Google's Dorks...

Google Dork is an employee who unknowingly exposes sensitive corporate information on the Internet. Google dork queries are built with the advanced search operators that IT administrators, researchers and other professionals use in their daily work to narrow down search engine results.

Because search operators can be strung together, an attacker can use complex queries to find information that was published on the Internet but was not meant to be found. The use of advanced search operators to find information that is not easily accessed through simple searches is sometimes called Google dorking or Google hacking. Google hacking is a computer hacking technique that uses Google Search and other Google applications to find security holes in the configuration and computer code that websites use. Google hacking involves using advanced operators in the Google search engine to locate specific strings of text within search results. Some of the more popular examples are finding specific versions of vulnerable Web applications.
The following search query will locate all websites that have the words "admbook" and "version" in the title of the website. It also checks to ensure that the web page being accessed is a PHP file.
intitle:admbook intitle:version filetype:php

Here is a PDF which you can use for more study.
Here is a list of 4000+ Google dorks.

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