In the earlier days of the Internet domain names (e.g., .com, .org) were generally more meaningful than they are today. Now there is often little distinction between a website with a .com or a .org domain. And while .edu indicates that a webpage is affiliated with an institution of higher education in some capacity, you should look more carefully as what that affiliation is (for example, a personal website of anyone who works or studies at that institution vs. the official website of a research institute affiliated with that institution).
In other words, examining a web site domain is one method in a multi-step process in evaluating a web site, but it is not always a gold standard methodology in determining the credibility of a web site. Just because a web site has an educational domain (.edu) it does not make it more credible than a .com or a .gov. Using lateral reading techniques can help you determine if a website is credible. In short, there is no shortcut to spot a bad website from a domain alone.
You may have heard in the past that you should avoid Wikipedia as a source. We (like Mike Caulfield) will instead encourage you to use Wikipedia, but to do so while recognizing both its strengths and its limitations. Most Wikipedia articles are highly accurate, as Wikipedia has editors who work to ensure that Wikipedia content adheres is its editorial practices, including providing evidentiary sources. Wikipedia articles that are longer and that are older tend to be of higher quality because they have been developed and improved over time by individuals who follow Wikipedia's best practices. That said, it's still true that someone can put inaccurate information on Wikipedia that is not immediately corrected. Wikipedia articles that are about contentious topics and that are undeveloped should be evaluated with greater care. You can also use the references at the end of a Wikipedia page to help you determine its level of accuracy.