Information is something we can encode, store and process in some physical systems using some physical interactions. Quantum information has features that is not shared by classical information: 1. **Intrinsic Randomness**: Can't predict outcomes even with the most complete possible knowledge of the state. It applies even when you have the most complete description. 2. **Uncertainty**: Measuring A influences the outcome of a subsequent measurement of B, Operators A and B does not commute. 3. **Entanglement**: The whole is more definite than the parts.