What is Quantum Computing

Recently IBM presented a Quantum Computer called IBM Q System One and they claim that they are at a quantum ready phase. So what is quantum computing and how will it affect our lives?

Classical computers work with bits while quantum computers work with qubits. By using the superposition of quantum states, just a few qubits can do the work of millions or even billions of qubits. This will make computation much faster.

Quantum computing will be useful in 1. Quantum Cryptography 2. Quantum Simulation 3. Making smaller computers (because of quantum tunneling, it becomes harder to make smaller computers)