A quantum computer performs calculations based on quantum mechanics, the behavior of particles at the subatomic level. Unlike conventional computers that use bits of 0s and 1s, quantum computers use quantum bits or qubits that can be 0 and 1 simultaneously. This superposition allows quantum computers to manipulate enormous combinations of states at once, potentially performing calculations millions of times faster than classical computers. If built, quantum computers could revolutionize computing in the 21st century by tapping directly into the vast potential of quantum mechanics.