WHY sub-machine guns?

I have always wondered why there are still submachine guns around... I mean we have full automatic pistols now. Easier to conseal, light way, and the list goes on.

thats what im always saying,but maybe there is things that we dont know such as easy to built safer anti water cheaper

The sub machine gun was developed in WWI to give field infantry the automatic fire rates of a machine gun chambered in the easier to carry and much cheaper pistol cartridges. The SMG has survived to this day as the preferred close combat weapon of many military special forces units and law enforcement agencies around the world. The SMG fills the roll between rifle and pistol, with the longer barrel of the SMG offering better accuracy at medium ranges than a pistol.