Entropy is a measure of disorder or randomness in a system. In thermodynamics, it quantifies the amount of energy in a physical system that is not available to do work. The second law of thermodynamics states that the total entropy of an isolated system can never decrease over time, which implies that natural processes tend to move towards a state of greater disorder.
In information theory, entropy represents the uncertainty or unpredictability of information content. It helps in understanding the efficiency of data encoding and transmission. Higher entropy indicates more unpredictability, while lower entropy suggests more order and predictability in the data.