This is basically trading currencies without holding the physical currency it self.
But yeah if u do that physically it counts as forex as well. But u are more like a foreign currency exchanger.

Forex is an abbreviation of Foreign Exchange.
This thread is about anything related to forex.
Shorting or holding foreign exchange has very little meaning or no meaning at all to be segregated into threads as, if you are holding a currency you are going to be shorting another currency because forex always works in pairs.

Good business, good money, but it is illegal. Beware.

EDIT: Unless you are licensed.

Yes it's illegal. You can check at the BNM website.