Wikipedia is a great tool, but it is not a scholarly source of information. Whether you are permitted to use it or not for a research project is up to your teacher and will depend on the project and your grade level.
Wikipedia is an open-source online encyclopedia. It is a marvelous resource for finding information on almost any topic. Most articles can be edited by anyone, which means that anyone, even those unqualified to write on a topic or jokers, can change most articles. This means that Wikipedia benefits from collective knowledge, but also that it is not a respected choice for research. Some teachers allow its use (i.e., it is generally acceptable for middle school and lower school purposes), but others discourage or disallow its use. Even if it cannot be a cited source for your research project, it is often a good place to start. It can provide a good overview of a topic, and the external links and references at the bottom of the articles often provide valuable sources for researchers.
John Green's series on Navigating Digital Information video on Wikipedia provides an excellent 10 minute overview explaining when and how to use Wikipedia to the best effect.