A quantum computer can, in a sense, check many answers at once

An ordinary computer bit takes one of two values: 0 or 1. A qubit, the basic unit of information in a quantum computer, can — thanks to superposition — exist in a state that is a combination of both values at once, until it's measured.

This lets a system of many qubits represent and, in a sense, process an enormous number of possible combinations simultaneously, instead of checking them one at a time the way a classical computer does.

This doesn't mean quantum computers are just "faster" computers for everything — for most everyday tasks, like browsing the web or editing a document, they offer no advantage at all. Their potential power shows up in very specific problems, like factoring large numbers or simulating quantum systems.

Measuring the final result "collapses" the superposition down to one single answer — which is why designing a quantum algorithm is largely about making sure the probability of getting the right answer is as high as possible at the moment of that measurement.