The forex market is not structured like a traditional exchange market such
as the New York Stock Exchange or the Chicago Mercantile Exchange.
Forex is a decentralized global marketplace where trades are cleared one
on one between trading partners. There is no central exchange, no pit full
of yelling traders, no big board of quotes on a New York street, and no
closing bell to ring. The pros and cons of an exchange-based market versus
off-exchange currency trading are debatable, but there are obvious differences
you should understand before trading in the forex market.
source :trading forex