Quotation marks
Putting quotation marks around a word instructs the Google search engine to look for that word exactly. The default search without quotation marks would retrieve results for that word along with results for any synonyms. For example, a search for the word coffee without quotation marks retrieves over 5 million results and a search for coffee with quotation marks retrieves over 1 million results. Quotation marks make the search more specific to an exact term. They can also instruct the search engine to retrieve results for a specific phrase, such as climate change, instead of the default which would be to retrieve results including both words but not necessarily next to each other.
Site type search
After typing in your keywords you can add the command site: followed by a domain type like .gov, .ca, .org, .edu or others to limit your search results to specific kinds of webpages. A search for "accessibility" site:.ca would retrieve results from Canadian webpages that include the word accessibility.
File type search
After typing in your keywords you can add the command filetype: followed by a file type that is indexed by Google, such as pdf, ppt, doc, or jpeg. A search for "coffee" filetype:ppt would retrieve any powepoint slides on the internet that include the term coffee.
You can find more information about search operators and other search tips form Google's help centre.