Centuries ago Europeans thought that all swans were white. That was the only kind of swan they had seen. However, explorers discovered black swans in Australia (and blacknecked swans in South America). Those discoveries proved that not all swans are white. The hypothesis, that "all swans are white" was falsifiable. It only takes one black swan to prove the "all swans are white" hypothesis wrong. Observations proved that the hypothesis was wrong.

But how easy is it to prove a hypothesis is correct?
How do we prove a hypothesis is true?
Well, proving a hypothesis true is a difficult thing to do especially in science. Indeed, it is actually unscientific to say that a hypothesis has been proven to be true. (Mathematicians can "prove" a hypothesis to be true, but that is because math proofs are really philosophical proofs.)

Imagine the embarrassed scientists of old Europe when an explorer brought home the first black swan! It was proof that they were wrong to think all swans were white. It was an honest mistake to make because all they had ever seen were white swans and that is precisely where they made their mistake. There is no way to find and observe every swan in the world! If you missed one, you cannot honestly say you have proven all swans are white.

But imagine those explorers had never found a black swan.
Imagine you had a (magical?) device that collected every swan in the world and delivered them to your door.
Imagine all of those swans were white.
Would that be proof that all swans were white?
Would you have proven the hypothesis, "All swans are white."?

1. Yes - this is positive proof that all swans are white. The hypothesis is true.

2. No- this is still not proof positive. The hypothesis has not been proven true.