A belief is an assumed truth. Something, that through our experiences and thoughts we assume to be true. This doesn’t mean that it is true. Your belief system isn’t necessarily accurate. Your brain is a large, pattern-matching organism that will unconsciously look for evidence to confirm and reinforce your beliefs – and prove you right!
Your beliefs are often your perception of the way things are and what you believe to be true. But this does not mean that your beliefs are actually true.