A qubit is the basic unit of information in a quantum computer, similar to a classical bit, but it can exist in both states – 0 and 1 – at the same time due to the principle of quantum superposition. This property allows qubits to perform multiple calculations simultaneously, drastically increasing the computational power and efficiency of quantum computers. In addition, qubits can be quantumly entangled, which makes it possible to execute complex algorithms that classical computers would perform much more slowly.