Generally, sites that end in .edu or .gov are reliable sources of information.
Sites that end in .org are run by organizations that most likely have an agenda, so you will have to be careful to check for bias.
For sites that end in .com, you will always have to evaluate the authenticity of the information you find there.
To search for results only with a certain domain (such as .edu or .gov):
In the search bar type:
Popular domains include:
gov (US government sites) mil (US military sites) edu (US academic sites)
org (organizations) com (commercial sites), state.nj.us (for US states sites)
To search for a specific file type, pdf, xls, doc, ppt, ...
"illegal aliens" filetype:.pdf
Use limits like intitle: or intext: to focus your search results
intitle:voter (the word voter must be in the title of the page)
allintitle:voter fraud (the words voter & fraud must appear in the title of the page)
To search within a number range
Number range searching
India “urban redevelopment” 2006..2007
“digital cameras” $300...$500
Using * as a wildcard operator when searching will search for missing words within your search phrase. For example: Remember, remember, the * of *
Google automatically searches for similar spellings (not synonyms) when you perform a search. For example: diet, dietary, and diets.
Using ~ will search for synonyms. For example: ~inexpensive will search for inexpensive, cheap, affordable, etc.