Google is an incredible tool for finding websites. But many of the websites that you find may not be reliable or authoritative.
When searching Google, you can limit your search to a certain domain. Educational sites (sites from educational institutions like universities and colleges) end with .edu. By limiting your search to sites with .edu, you can usually retrieve reliable websites. Government sites may also contain useful information including primary documents and statistics. You can limit your search to government sites by using .gov.
To limit your search, type site:edu or site:gov at the end of your search in Google. Note that there are no spaces in this. Typing in site: edu will not work.