The basic requirement for a topic to have its own article is: significant coverage in reliable sources that are independent of the subject. Here's a little more detail about how this rule is interpreted by Wikipedians:

• Significant coverage means that sources address the subject directly in detail. Significant coverage is more than a trivial mention, but doesn’t have to be the main topic of the source material. On the other hand, a single-line mention in a text would be non-significant.

• Reliable sources, for the sake of establishing notability, generally means at least two independent secondary sources from reputable publishers with a reputation for fact-checking and accuracy. These don’t need to be in English, or available online. Multiple sources from the same author or organization are considered a single source for establishing notability.

• Independent of the subject excludes works produced by those affiliated with the subject or its creator. For example, self-publicity, advertising, self-published material by the subject, the subject's website, autobiographies, and press releases are not considered independent.