Wikipedia touts itself as the "encyclopedia that anyone can edit," but is it truly a scholarly source that should be used in a professional or educational situation? No.
Anyone can edit an entry in Wikipedia. That means you, and that means me, and that means your friend's younger sibling who is in a bad mood. The impact of this is that the information given is not always correct. You may have heard me tell the story that another teacher librarian told me. She was in a fifth grade class on the day they presented their reports on a country. Each scholar had created a poster with the name of the country, ethnic food eaten there, geography, and major religion practiced, and was presenting them to the class. That day, a student stood up in class and showed off his poster of England, telling the class that it is an island, they eat fish and chips with vinegar (yum!), and so on and so forth. Finally, he shared that the religion most practiced in England was that of the Jedi. The teacher librarian and the teacher were shocked! When asked, he stated that he got his information from--you guessed it!-- Wikipedia. (Perhaps he read this article and got confused?) Needless to say, when I checked Wikipedia, the Jedi comment has already been removed.
Now, I'm not saying Wikipedia is bad--heck, I even use it when I want to quickly look up a band I'm interested in. But that's different than writing a professional or educational paper; when I write those, I certainly do not use Wikipedia. What I want to get across to you is that Wikipedia is not an authoritative source. You can't say that this specific person researched the article you're citing, because a lot of people have participated in it's construction. It's not possible to verify that all facts are actually true because anonymous people can edit the article.
If you want vetted websites that are all scholarly sources, check out our Virtual Reference Desk. These websites are arranged alphabetically and cover all sorts of topics. It even has links to real encyclopedias. If you use the Virtual Reference Desk you will never be like that boy who stood up and gave false information--you'll be able to deliver your information confident that it's correct.