Knowledge and belief

I often read about people claiming to "know" one thing or another. But do they really know it?

When we hear something second-hand from another person (or many other people- often repeating from the same, sometimes dubious, source) can that really be classed as "knowledge"?

To me, to "know" something implies the certainty that comes from first-hand experience.

Anything we hear from external sources that we accept as truth I would describe as a "belief".

I don't think we can ever be 100% certain of information coming from other people, even ones we have learnt to trust, so I don't think it's accurate to describe information gained that way as true "knowledge", the way many seem to do.