Prop trading means trading with a firm's money and keeping part of what you make. "Prop" is short for proprietary - the capital belongs to the firm, not to clients and not to you. Your stake in the retail model is the evaluation fee; your upside is the profit split, typically 70-90%.
The plain-English test: ask whose balance sheet absorbs the loss. If a bad month hurts the firm's account (or, more often today, its simulated ledger), you are looking at prop trading. If a bad month hurts investors who bought in, you are looking at a fund - a different product with regulation the prop model largely avoids.
Why the meaning matters in practice: it explains the rules that surprise new traders. Because the firm carries the tail risk, it enforces drawdown limits, consistency rules and payout gates - the vocabulary our drawdown hub and consistency rule guide define. The full walkthrough of the model: what prop trading is.
General investor-education material on trading risks is maintained by the SEC.
Part of the beginner glossary cluster and the full prop firm glossary.