Most of you have to wear a uniform but in the United States it's pretty normal to be allowed to wear your own clothes to class.
In fact some schools are so relaxed, even pyjamas are allowed in the classroom.
Imagine that! You wouldn't even have to get dressed in the morning!
Here in the UK, 82% of schools have a uniform, which pupils have to wear or risk getting into trouble.
The uniform will generally have a blazer or jumper with a logo on it to show what school you belong to.
When it comes to things like skirts, trousers and shoes, there are often no set brand that you have to wear.
But there are generally guidelines about what kind of trousers or shoes the school will accept as part of the uniform.
In 2017, Evanston Township High School in the state of Illinois brought in a dress code which allowed students to wear everything from crop tops, and torn jeans, to hats, and even pyjamas.
The idea seems to be spreading.
A school in California is introducing a similar policy for this school year.
The school said it was embracing an 'anti-dress code' where nearly everything is allowed.
It says the idea is that pupils can dress without "fear of unnecessary discipline or body shaming".
The only rules are that private parts of the body must be covered by a non see-through material, and clothes showing a violent or offensive messages are banned.
Back in 2016, 50 children in Kent were sent home from school on the first day back after the holidays because they weren't wearing the correct uniform.
Reasons for turning children away from Hartsdown Academy included 'inappropriate' shoes and 'skin-tight' jeans and skirts.
People have argued this is body-shaming. Other schools are taking a different and much more relaxed approach.
What do you think? Should you be allowed to wear what you want or do you think uniform is a good thing?