The principle of entropy in common vocabulary: it’s why things naturally tend toward disorder: a hot cup of coffee cools as its heat disperses into the room, never spontaneously reheating itself; an ice cube melts into water, but the water doesn’t refreeze on its own in a warm glass. It’s why eggs break and never unbreak.
On the other hand, living things reverse that process, actually leveraging entropy to produce its opposite: negentropy. Living things consume lower forms (living or not) and build organized structures like eggs, themselves, houses, databases, and loving relationships.
Entropy, described by the Second Law of thermodynamics, covers a lot of territory and is stated in negative terminology for that reason. It’s Physic’s definition can be broken into 3 statements: 1) No process is possibe that solely transfers heat from a lower temperature body to a higher temperture one; 2) It is impossible to construct a device that operates in a thermodynamic cycle and produces no effect other than the extraction of heat from a reservoir and the performance of an equal amount of work; and 3) In any isolated system, the total entropy S never decreases over time: ∆S ≥ 0, where equality holds only for reversible processes.