There are some arguments both for and against it
One the one hand, some schools have rules and it is compulsory to wear uniform. These rules are usually for small children who go to primary school, for example.
On the other hand, many pupils disagree with uniforms, for example teenagers, who are very worried about clothes, and sometimes they go against the rules and they wear clothes that are not appropriate at school.
To sum up, uniforms are a good idea for small children but I think the students of high schools shouldn't have to wear uniforms because I think that we are responsible enough to be able to choose our clothes.