Presearch is the informal searching you might do on a topic before you start your deeper, more focused research. When you're doing your presearch you're finding background information on your topic and creating context for your topic and how you might want to approach it.
You can use ANY kind of presearch resources you want, including Wikipedia, as long as you keep in mind that presearch is informal and some of the resources that you use to educate yourself about your topic are not necessarily appropriate for a college-level paper.
Some other good places to start your presearch are Google, GoogleNews, and some of the library's "Getting Started" databases (encyclopedias, dictionaries, and other reference sources).
It's perfectly okay to look at a Wikipedia page to learn more about your topic when you're doing presearch, but you would not want to use this as a formal resource for your paper. What you can do is use Wikipedia's links and references to locate more authoritative and credible sources. In many cases you can find more authoritative resources, such as books and published articles from these references.
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