Backtesting – The built-in Strategy Tester in MetaTrader allows simulating an Expert Advisor’s performance on historical data. In MT4/MT5 you can run EAs on past quotes to evaluate and optimize them without risking real capital. The Strategy Tester can use different modeling modes (every tick, 1-minute bars, etc.), optimize input parameters, and provide detailed reports of trade outcomes. (MT4’s tester is single-threaded and limited to one symbol at a time, while MT5’s tester is multi-threaded and multi-currency with advanced optimization features.)