MetaTrader 4 (MT4) is a popular trading platform used by forex traders to analyze and trade in the financial markets. It supports two types of files for automated trading: EX4 (compiled) and MQ4 (source code). The EX4 file is a compiled version of the MQ4 file, which means that the MQ4 file is converted into an executable EX4 file that can be run on the MT4 platform.