I don't know if this is the right question for this subreddit, but I guess I have to ask the professionals. Very many people use Wikipedia to quickly search for information they need, but when is a Wikipedia article reliable? What are the standards for an article to call it so? Does it need many references to books and other articles or is Wikipedia not a 'reliable' source at all? Since authors are anonymous, does this make a difference? Thank you for the answers and sorry for my bad grammar.
Wikipedia articles are never "citable". That is, if you want to substantiate your claims in an academic context, wikipedia articles are worthless. Since they can change over time, at the very least, you need to refer a certain version of a wikipedia page. But even then, the fact that everybody can edit them and there is no review process in place before publication, makes them frowned upon for citations.
That being said, they definitely have a place. They are great to get an overview over a topic, and they can often cite sources that themselves are citable. You then get some starting points from which you can "branch out" from the wikipedia article, find cites in those cites, etc.
The reliability also depends on the topic. Some topics have a higher "crackpot factor" than others. Articles about engineering, math, and natural sciences are, by and large, quite reliable, because they deal with cold, hard facts. Biographical articles and, sadly with regard to this subreddit, history articles are much more susceptible to "original research" and biased presentations. Political articles generally carry the highest risk of biased presentation.
By and large, wikipedia articles are surprisingly good at giving a thorough overview. Blatantly biased articles are often less a problem than those growing a ridiculous list of "some people claim that X, while some people claim that Y". It's then basically up to your media literacy skills to gauge what you consider relevant and reasonable.
Never, wiki articles are not reliable in an academic setting as anyone can edit them at any time.
At my university, you would have to cite and link directly to a permalink to wikipedia, and I am surprised it hasn't been mentioned here before. The permalink makes sure that the reviewer gets to the exact same page that you used. Wikipedia offers this in the sidebar.
You may be interested in some earlier discussions of Wikipedia