Wikipedia:Be a reliable source
This is an essay.
It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints.
The term "reliable sources" gets thrown around a lot. While Wikipedia has a definition of a reliable source, many editors have their own.
An object everyone should strive for is to be one.
How to be a reliable source
The best way you can be a reliable source is to strictly adhere to the guidelines pertaining to them. This means to cite all information you add to articles, to be sure all information is verifiable, and not to include original research in your additions. If you get known for being a reliable source--that is, for using authoritative sources published by reputable publishing houses, it is more likely that your edits will be trusted.