Wikipedia: useful as a starting point, but be critical
Wikipedia is an accessible and often up-to-date source. For an initial orientation on your topic, it’s a great place: you can quickly find clear information, key concepts, and often references to more in-depth sources.
But be careful: Wikipedia is an open source. Anyone can write and edit articles. This makes the information vulnerable to errors, biased interpretations, or even deliberate misinformation.

Example: the toaster hoax
In 2012, two bored British students started a Wikipedia hoax during a dull lecture: they invented a person named Alan MacMasters and gave him a prominent role as the inventor of the electric toaster. They edited the Wikipedia article about the toaster and even created a separate page for this fictional character. It took almost ten years before someone saw through the hoax. Meanwhile, the false information was picked up by newspapers, blogs, and even museums.
Read more about this hoax at BBC News.
How to use Wikipedia responsibly
Wikipedia is usefull, as long as you remain critical. Use it as a starting point, not as a final source.
Check a second source to verify the quality of the information.
In well-written Wikipedia articles, the sources used are listed at the bottom of the page. Consult and cite these sources, but also check their reliability (CRAAP test).
If no sources are provided, it’s better not to use the information from Wikipedia.