Backtesting a Forex robot or a trading strategy is to test its performance to get gives an idea about how it could react with the market in the past and if that reaction and performance was good, it should theoretically continue that in the future, hence the importance of backtesting is non-ignorable! To Backtest, you must have saved tick data to your computer commonly obtained either via MT4 history center or Dukascopy, the historical data are free and you can get it easily via MT4 as we will .