Epistemologists talk about various epistemic features of belief.
Anyway, of these four terms, the term that has been most widely used and discussed, in the past twenty years or so anyway, is justification . But in epistemology it's mainly beliefs that are said to be justified or not. The idea is that we want to be responsible about what we believe. We don't want to just go off and believe anything . In some sense, it's bad just to believe whatever happens to pop into your mind.