Limit order
An order to buy or sell at a specified price or better, which may not fill if the market never reaches it.
A limit order sets the maximum price a buyer will pay or the minimum a seller will accept. It fills only at that price or better, so the trader controls the price but not whether or when the order fills. A buy limit below the market and a sell limit above it rest in the order book until matched.
On our site, limit prices are read against the depth of a quote. A large resting limit order can be read as a level of interest until it is filled or cancelled.
Traders care because limit orders trade price control for execution certainty. Market orders fill quickly but accept whatever the book offers.
Worked example (illustrative numbers, not real data): a trader places a buy limit at 99.90 when the ask is 100.05. No fill occurs unless the price falls to 99.90. If it drops to 99.85, the order fills at 99.90 or better.