Do you smile when you’re happy? Research shows that kids smile about 400 times a day. Adults only smile about 30 times a day. It sounds way more fun to be a kid!

It feels easy to smile. Sometimes you don’t even control your smile – it just happens. Smiling uses around 15 muscles. Those small muscles in your face work together to create your expression.

It takes a lot more muscles to frown. Scientists say you use around 50 face muscles to make that grumpy face. Maybe that’s why you’re grumpy – your face is working too hard!

You’ve probably noticed that not all smiles are the same. Researchers have named 19 different kinds of smiles. They can be divided into two groups.

One group is called “sincerely felt smiles.” These are the expressions you make when you are truly happy about something. They are the ones that often happen on their own, without you even thinking about it.

The other group is called “polite social smiles.” You smile this way when you want to show good manners. You also smile like this when you say, “cheese!”

You might think that a smile is universal. But some cultures smile more than others. Cultures have different rules about when it is okay to smile and when you should not.

Some cultures rarely show smiles outside of their families. But despite these differences, smiles are still used to show happiness. According to one scientist, “a true smile is when the mouth and the heart coordinate with each other.”