Algorithmic trading is simply the use of pre-programmed sets of rules for determining when to open and close positions on a given market.
Trading algorithms can either replace human decision making to completely automate the trading process, or they can generate signals that have to receive final authorization from a human being. Both the MT4 and MT5 trading platforms feature advanced algorithmic trading functionality.
On these platforms, they are called Expert Advisors (EAs). There’s a vibrant community of programmers creating, testing and sharing Expert Advisors. The MT4 and MT5 platforms provide some advanced features for their creation, backtesting and deployment.