The rest of this pillar reads more clearly once the vocabulary is settled. These are the terms behind cost-beating discipline, defined plainly and without hype. None of them is jargon for its own sake — each one is a real line in the decision about whether a signal is worth taking.
Edge
The gross move a signal expects to capture if it is correct. The edge is the starting figure every cost is subtracted from. A large edge means nothing until friction has been taken out of it.
Spread
The gap between the best bid and the best ask. You cross it the instant you trade at market — buying at the ask, selling at the bid — so it is a cost paid on both entry and exit, before any fee.
Slippage
The difference between the price you expected and the price your order actually filled at. Slippage grows when liquidity is thin, because your order has to walk through several price levels to fill.
Fees
The maker or taker charge the exchange applies to each side of a trade. Small per trade, but paid every time, which is why they matter most to anyone tempted to overtrade.
Safety buffer
A deliberate margin added on top of the known costs, to account for the fact that real fills in volatile conditions rarely match the textbook. The buffer keeps the cost estimate honest rather than optimistic.
Cost-to-beat
The four costs above, stacked together, into the single hurdle a trade must clear before it makes anything. If the edge does not exceed the cost-to-beat, the trade is a net loser no matter how good the direction looks.
Transparent rejection
A signal whose edge failed to clear its cost-to-beat, logged on the record with the line that failed. A rejection is the rule working, not a fault, and nothing about it is hidden.
See these terms in action in how to read a signal cost breakdown and the anatomy of a rejected signal. For the origin of these costs in plain market terms, the education pillar covers the fundamentals. Nothing here is financial advice or a promise of profit.