“If you need to cry you should cry,” Maira Kalman wrote in her marvelous philosophical children’s book. But what is it, exactly, that makes us need to cry and are all tears created equal? That’s what the TED-Ed team explores in this wonderful animated primer on why we cry and the three types of tears:

When someone is either too sad or too happy, it feels like a loss of control — which can be dangerous. So emotional tears are sent in to stabilize the mood as quickly as possible, along with other physical reactions, such as increased heart rate and slower breathing. But scientists still aren’t sure exactly how or why the tears are helpful. They may be a social mechanism to elicit sympathy or show submission. But some studies have also found that emotional tears contain higher levels of stress hormones, such as ACTH and Enkephalin, an endorphin and natural painkiller.

Complement with the science of sobbing and emotional tearing, then treat yourself to more illuminating TED-Ed primers exploring how the clouds got their names, why some people are left-handed, how melancholy enhances creativity, what makes a hero, how you know you exist, and why playing music benefits your brain more than any other activity.