The first thing you think after said "uniforms" is school: in many schools in the world uniforms are used, and so is in Magic world.
Hogwarts uniforms uses different colours for every house, so everyone can know how are you: example, a Slytherin suddenly recognizes a Gryffindor by its golden and red colours, and that recognizes the first by green and silver colours.
Uniforms are the first thing you find in the bedrooms and they are mandatory during school times. They are accessorized with some complementary items, like scarves, hats, ties, cloaks and more. Personally, what I prefer is scarves, because their brilliant colours, every house.
Uniforms are different from girls to boys: girls have skirts and something more suitable for "her" while boys have trousers and cloaks. But both have ties.
Clothes changes from movie to movie: until 3rd movie uniforms have been the same, after that they started to change, probably for the higher age too, and, example, the fifth movie has large cloaks the previous have not.
Quidditch has its own uniforms too! They have large cloaks, brilliant colours for their house.