MT4 ECN Bridge is a technology that allows a user to access the interbank foreign exchange market through the MetaTrader 4 (MT4) electronic trading platform.
MT4 was designed to allow trading between a broker and its clients, so it did not provide for passing orders through to wholesale forex market via electronic communication networks (ECNs).
[1] In response, a number of third-party software companies developed Straight-through processing bridging software[2] to allow the MT4 server to pass orders placed by clients directly to an ECN and feed trade confirmations back automatically.
A number of software companies attempted to develop bridging technology that allowed the broker to connect the MT4 server to an ECN.
There are two main types of bridge technology which effects the way orders are processed: the STP and ECN models.