A program that trades automatically on the MetaTrader platform. The common name for a forex bot.
An Expert Advisor, or EA, is software that runs inside MetaTrader 4 or MetaTrader 5 and places trades by its own rules. Most forex bots sold online are EAs.
An EA does exactly what it was programmed to do, including in conditions its author never considered. Before running one with real money, find out what strategy it uses, whether every trade has a stop loss, and whether a real-money track record exists.
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Educational content only, not financial advice. Trading forex involves substantial risk of loss.