What is qubit?

A qubit, short for quantum bit, is the fundamental unit of information in quantum computing. Unlike classical bits in traditional computing that can be either 0 or 1, a qubit can exist in a state that is a superposition of both 0 and 1 simultaneously due to the principles of quantum mechanics. This property allows quantum computers to perform complex calculations and solve certain problems exponentially faster than classical computers by leveraging quantum phenomena like superposition and entanglement.