Major contributors of information to the Internet can generally be organized into 4 large categories, each of which uses a different ending in their "domain" name. Domain names are critically important for online researchers, as they quickly give you a significant hint about the origin, intent, and reliability of a website:
Since so much of the Web is commercial (.com), and commercial sites sometimes want to sell you something (but not always), it is handy to know how to restrict a search to educational institutions (.edu), organizations (.org), or government (.gov) sites, which may be more reliable sources of information.
Please watch the following video (2:17) for a brief demonstration of a variety of Google search tips, including the trick to limit by domain:
Google Scholar is a Google tool that allows for you to limit your search to scholarly literature. Search results include journal articles, books, theses, abstracts and court opinions from academic publishers, professional societies, universities and other websites. Google Scholar results are very likely to be appropriate for use in academic research papers! Note that some of the results are from undergraduates. Evaluate the author of the papers to make sure they are experts in the field and not undergraduates or those writing their Master's thesis. If you happen upon a dissertation by a Ph.D candidate, those are typically acceptable. Check with your instructor just in case.
Many articles found in Google Scholar will not provide the full text of the article for free. Instead, they will ask for a fee to read the article. You should not cite articles that are not available in full text - You should be able to freely access and read the full article if you want to include it as a source for your paper. If there is a link to the right of the title, it is most likely free from that link. Avoid paying for the article! If you cannot find it for free, ask a librarian if they can get it for you.