- I believe the Nancy Drew videogame series is awesome.
- I don't believe soccer is an interesting sport.
- "I believe I can fly. I believe I can touch the sky. I think about it every night and day."--R. Kelly.
According to Plato, beliefs become knowledge when they are justified. If you have a good reason for believing something, then your belief becomes knowledge. For example, I believe Abrahamn Lincoln died in 1865. I believe this, because I read it in a book. This means I know Abraham Lincoln died in 1865, and I can confidently state that as a fact, not as an opinion or an unjustified belief.
Obviously, it is possible to have false knowledge. That is what you call it, when a person believes something which is not true. It does not matter how justified their belief is; even if you have a good reason to believe something false, it is still false knowledge.
10% of the time, we believe things because we saw them or figured them out in our minds. 90% of the time, we believe things on the testimony of other people. Those beliefs include everything that happened before you were born, and everything that happens outside of your current location. You weren't around to see those things yourself, but you still believe they happened.