Laughter is the sound people make when something strikes them as funny or delightful. It might burst out as a quick giggle, a belly laugh that shakes your whole body, or anything in between.

Laughter happens automatically when something tickles your sense of humor: a silly joke, a friend's goofy face, or a cat doing something unexpectedly ridiculous. You can't really force genuine laughter (though you can fake it). Real laughter just happens when joy or amusement overwhelms you.

Scientists have found that laughter is contagious. When one person starts laughing, others often join in, even if they missed the original joke. That's why comedy shows include laugh tracks and why it's more fun to watch a funny movie with friends than alone.

Laughter also serves as social glue. When people laugh together, they feel closer and more connected. A classroom full of laughter usually means students feel comfortable and happy. Shared laughter can turn strangers into friends and help friends get through tough times together.

The phrase laughter is the best medicine suggests that laughing can make you feel better when you're sad or stressed. While laughter won't cure illnesses, it can lift your spirits and help you cope with difficulties.