A basis point is 1/100th of a percentage point: 100 bps equals 1%, 15 bps equals 0.15%. Trading costs, fees, and spreads are almost always quoted in bps rather than raw percentages, since the numbers involved are typically small enough that "0.15%" invites rounding errors and misreads that "15 bps" doesn't.
It's the unit zengtrade's own cost model is expressed in: a 15bps round-trip cost figure means exactly that, 0.15% of position value lost to fees and slippage on the full entry-plus-exit round trip, applied identically to every backtest and every live paper fill rather than varying by context.
Reading strategy performance in bps terms also makes cost comparisons concrete: a strategy generating an average 40bps of edge per trade against a 15bps round-trip cost has a real margin of safety; one generating 18bps of edge against that same 15bps cost is trading on the edge of profitability, however good its win rate looks.
Educational content, not investment advice. zengtrade is paper-first and non-custodial.