What is a forex Expert Advisor (EA)? A plain-English guide

How an Expert Advisor works

An EA is attached to a chart in MetaTrader 4 or MetaTrader 5. On every price tick it reads market data, checks its rules, and can open, modify or close trades through your broker without you clicking anything.

The rules are written in code. They might use indicators, price levels, time of day or a combination. The EA does exactly what the code says, which is both its strength and its limit.

What an EA does well

Automation removes some human weaknesses and adds some convenience.

• It follows its rules every time, without hesitation or emotion.
• It can watch the market around the clock while your computer or VPS is running.
• It applies position sizing and stop loss rules consistently.

What an EA cannot do

An EA does not remove risk. It cannot predict the future, and a strategy that worked in the past can stop working when market conditions change. It also only works when the platform is running, connected, and allowed to trade.

Trading leveraged products carries a high risk of loss. Never trade money you cannot afford to lose, and read the product's risk disclosure before buying.

What you need to run one

The basic requirements are small.

• A MetaTrader 4 or 5 account with a broker that allows automated trading.
• The EA file (.ex4 or .ex5) and, if provided, a setfile with recommended inputs.
• A computer or VPS that stays online while the EA trades.

How to start safely

Install the EA on a demo account first and let it run through different market conditions. Read its manual, understand its inputs, and only then consider a small live account with a lot size you are comfortable with.