Edge
A statistically demonstrable advantage in a specific market setup — the reason your strategy should make money over a large sample.
In trading, edge is a repeatable, quantifiable advantage: a setup that has historically produced a positive expected value over a large sample of trades. Without edge, position sizing and risk management are just slowing the inevitable. With edge, they compound it.
Edge can come from many sources — a technical pattern with historical follow-through, an informational advantage, a structural one (market-making, arbitrage), or a behavioural one (exploiting others' biases). Most retail traders' edge, if it exists, is behavioural: executing a simple strategy consistently while others cannot.
The honest question every trader must answer: "Have I verified my edge on sufficient data, or am I trading on a sample size too small to distinguish skill from luck?" If the sample is under 50-100 trades, you do not know yet.