Google Hacking, a.k.a. Google Dorking, is a computer hacking method that uses the Google search engine and other Google applications to find, in general, one or both of the following: software vulnerabilities and   misconfigurations by websites. On top of that, search queries on Google can be used to gather information for arbitrary or individual targets, discover error messages that disclose sensitive information, or seeking files containing credentials and other sensitive data. The search can also be limited to specific pages on a specific site, or it can search for specific information across all websites, giving a list of sites that hold said information.

Google hacking itself can be traced back to 2002. Johnny Long, an American computer security expert, author, and public speaker, began to uncover “unique” Google search queries. He dubbed this list of “unique” queries Google Dorks, and it grew into a large dictionary, before eventually converted into a database. Currently, many hackers also employ other search engines beside Google, such as Bing and Shodan. In fact, the latter is more oriented for searching crucial data, but the comprehensiveness of the results may not be as high as other, more widely-used search engines.

For instance, the following search query will list SQL files (filetype:sql) available that have been indexed by Google on websites where directory listing is enabled (intitle:"index of"). The database can be accessed through https://www.offensive-security.com/community-projects/google-hacking-database/ or https://www.exploit-db.com/google-hacking-database/.

It is possible to hide some of your information from Google, therefore preventing public viewing. One such method is to directly ask Google to uncache your information. To do that, one can visit https://www.google.com/remove.html and follow the steps from there.

Source: https://www.acunetix.com/websitesecurity/google-hacking/; https://searchsecurity.techtarget.com/definition/Google-hacking.