There's nothing more convenient than Wikipedia if you're looking for some quick information, and when the stakes are low (you need a piece of information to settle a bet with your roommate, or you want to get a basic sense of what something means before starting more in-depth research), you may get what you need from Wikipedia. In fact, some instructors may advise their students to read entries for scientific concepts on Wikipedia as a way to begin understanding those concepts.
Nevertheless, when you're doing academic research, you should be extremely cautious about using Wikipedia. As its own disclaimer states, information on Wikipedia is contributed by anyone who wants to post material, and the expertise of the posters is not taken into consideration. Users may be reading information that is outdated or that has been posted by someone who is not an expert in the field —or by someone who wishes to provide misinformation. While Wikipedia editors do correct misinformation, observers have found that they don’t catch everything—at least not right away.
Sometimes inaccurate information is posted to Wikipedia on purpose, as a hoax. In some well-documented cases, this inaccurate information continues to spread when people take it from Wikipedia and use it in books and articles.
If you do start with Wikipedia, you should make sure articles you read contain citations–and then go read the cited articles to check the accuracy of what you read on Wikipedia. For research papers, you should rely on the sources cited by Wikipedia authors rather than on Wikipedia itself.
You can find more information about the errors that have been caught on Wikipedia on the Wikipediocracy site.
There are other sites besides Wikipedia that feature user-generated content, including Quora and Reddit. These sites may show up in your search results, especially when you type a question into Google. Keep in mind that because these sites are user-authored, they are not reliable sources of fact-checked information. If you find something you think might be useful to you on one of those sites, you should look for another source for this information.
The fact that Wikipedia is not a reliable source for academic research doesn't mean that it's wrong to use basic reference materials when you're trying to familiarize yourself with a topic. In fact, the Harvard librarians can point you to specialized encyclopedias in different fields that offer introductory information. These sources can be particularly useful when you need background information or context for a topic you're writing about.