What Is an Expert Advisor (EA)?
An Expert Advisor is a program that runs inside MetaTrader 4 or 5 and trades automatically, following a fixed set of rules — with no discretion, no hesitation, and no deviation from what it was told to do.
What it actually does
An EA watches the market on a chart and checks its rules on every price tick or every new candle, depending on how it's written. When a condition matches — say, a moving average crossover, or a price sweep of yesterday's high — it places, modifies, or closes a trade automatically, through MetaTrader's own order execution.
It doesn't “think” or adapt beyond what its code defines. If a rule is wrong or incomplete, the EA executes the wrong or incomplete rule exactly as faithfully as it would execute a correct one.
What it needs to run
- checkMetaTrader 4 or 5 installed and running
- checkThe compiled EA file (.ex4 or .ex5) placed in the correct Experts folder
- checkAlgo Trading / AutoTrading enabled in the terminal
- checkThe terminal open and connected — an EA stops working the moment MetaTrader closes
That last point is why people running EAs long-term usually end up on a VPS — a remote computer that keeps MetaTrader open 24/7 even when their own laptop is off.
What it isn't
An EA isn't a guarantee of profit, and a well-built one isn't proof a strategy works — it's proof the strategy's rules are being executed correctly. Whether those rules are actually profitable is a separate question, answered by testing on real historical data and, eventually, a demo account.
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