Why backtesting?
You need to prove your strategy before using real money on it.
Most people find ideas on the internet and use real money to invest without testing
Better and faster than paper trading
How to backtest?
If you know how to code… FX tester
If you don’t know how to code… Manually
KPIs
Win %, Loss %
Win $, Loss $
Frequency and transaction cost
5 to 10 years of data