Entropy is a measure of disorder or randomness in a system. Scientists use this concept to describe how things tend to become more mixed up and disorganized over time.

Think about your bedroom. When it's clean, everything has a place: books on the shelf, clothes in the drawer, toys in the bin. That's a state of low entropy, high organization. But as you live in your room, things gradually spread out. Books end up on the floor, clothes pile on a chair, toys scatter everywhere. That's entropy increasing: the room is becoming more disordered. Cleaning your room means reducing entropy by putting energy into organizing things again.

Entropy shows up everywhere in nature. When you drop a glass and it shatters, entropy increases dramatically. The organized glass becomes randomly scattered pieces. Notice that the reverse doesn't happen on its own: broken glass doesn't spontaneously reassemble itself. This is because the universe tends to move toward higher entropy, not lower.

In physics, entropy helps explain why some processes usually go one direction. Heat flows from hot objects to cold ones, not the reverse, because that increases entropy. A melting ice cube increases entropy as its organized crystal structure becomes randomly moving water molecules.

Scientists discovered that entropy in an isolated system never decreases over time, a principle called the second law of thermodynamics. It's why you can't unscramble an egg, why perfume spreads throughout a room, and why maintaining order requires constant effort.