Quantum computers?

The following is a transcript of an answer that I posted on Stack Overflow in response to the question:

I read a while back that quantum computers can break most types of hashing and encryption in use today in a very short amount of time (I believe it was mere minutes). How is it possible? I’ve tried reading articles about it but I get lost at the “a quantum bit can be 1, 0, or something else”. Can someone explain how this relates to cracking such algorithms in plain English without all the fancy maths?