Qubits, or quantum bits, are the fundamental units of information in quantum computing. Unlike classical bits, which can be either 0 or 1, qubits can exist in a state of superposition, allowing them to represent both 0 and 1 simultaneously. This unique property enables quantum computers to perform complex calculations much faster than traditional computers. Additionally, qubits can be entangled, meaning the state of one qubit can depend on the state of another, no matter the distance between them. This phenomenon is crucial for quantum algorithms and protocols, such as those used in quantum cryptography and quantum teleportation.