What is the territorial conflict in the south china sea about?

The dispute in South China involves a dispute about the territories around the sea. The dispute involves Spartly, Paracel islands and boundaries of gulf of Tonkin, and some other features of south china sea, which certain states namely Malaysia, Philipinnes, Vietnam, Brunei, China and Indonesia.

The region claim to be theirs since it is a route of a large amount of trade that happens every year and it accounts to be third largest trade route of water in the world.