Every trade starts with an order. Choosing the right type affects the price you get, whether you get filled at all and how you are protected when the market moves fast.
Market order
Buys or sells immediately at the best available price. You are sure to be filled, but not of the exact price, especially in fast markets or around news.
Limit order
Buys below the current price or sells above it, at your chosen price or better. Useful for entering at a level (for example, buying at support). You may not be filled if price never reaches it.
Stop (entry) order
Buys above the current price or sells below it, once price reaches your level. Useful for breakout entries. In fast markets it can be filled worse than the stop price (slippage).
Stop loss and take profit
Attached to an open position: the stop loss closes it at a loss if price reaches your invalidation level; the take profit closes it at your target. In a prop challenge, a stop loss should be set on every trade at entry.