Interference happens when something gets in the way and disrupts what you're trying to do. When your little brother keeps interrupting while you're doing homework, that's interference. When static makes it hard to hear a radio station clearly, you're experiencing interference in the radio signal.

In sports, interference has a specific meaning: when a player illegally blocks or hinders an opponent who's trying to make a play. In football, if a defender pushes a receiver before the ball arrives, that's pass interference. In baseball, if a base runner deliberately blocks a fielder trying to catch the ball, the umpire calls interference.

Scientists use the word differently when describing waves. When two waves meet, they create an interference pattern: sometimes they combine to make a bigger wave, and sometimes they cancel each other out. You can see this when ripples spread from two stones dropped in a pond: where the ripples meet, the water gets choppy in interesting patterns.

The key idea connects all these meanings: something is blocking, disrupting, or mixing with something else. Whether it's a distraction keeping you from concentrating, a rule violation in sports, or waves colliding in physics class, interference always involves one thing getting tangled up with another and changing the expected result.