Entropy is a measure of:

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Entropy quantifies how spread out energy is among all the possible microscopic arrangements of a system. When a system is highly ordered, there are only a few ways to arrange its components, so entropy is low; when components are free to move and mix, there are many possible arrangements, and entropy is high (a gas has higher entropy than a solid). It isn’t a measure of how much energy the system contains, nor of how much energy is available to do work—that distinction comes from internal energy and free energy concepts. Entropy isn’t the equilibrium state itself; diffusion and other processes tend to increase entropy, moving the system toward maximum entropy under the given constraints. In biology, this idea helps explain why living systems continually exchange energy with their surroundings to maintain order locally while contributing to greater disorder overall.