Somewhat confusingly, Google does not have an official list of search operators. The “Refine Google searches” page on Google’s support website explains the concept but lists just three of the most popular operators. Those are using quotation marks around the search term to specify you’re looking for an exact match, putting – (a minus sign) in front of a word or phrase (in quotes) to exclude it from the search, and Google Site Search, where you can limit a search to a specific website with the “site:” operator, like site:SlashGear.com.
Where things get really interesting is when you can mix and match these with other operators. You can use * (an asterisk) as a wildcard, and combining it with site search lets you limit searches to specific top-level domains, like using site:*.gov to only search U.S. government websites. You could then match this up with the “filetype:” operator to tailor a search that’s narrowed down to government-hosted PDFs (“filetype:pdf”), Microsoft Word documents (“filetype:doc”), or even Excel spreadsheets (“filetype:xls”). Not all public records hosted by government websites are fully indexed by Google, but it’s a great way to dig through large quantities of official documents.