A type of stock market order you can make with a broker to buy or sell a stock if it's market price reaches a specified threshold. Distinguished from market order.

For instance, if RHAT is currently trading at 85, I might put in a limit order to sell all my RHAT if its market price reaches 100.

There is usually a time limit on these orders so that if the threshold is not reached within a certain time, the order expires. (Brokers tend to have a maximum time limit, so that unrealistic orders are eventually flushed out of the system.)

WTF was this a nodeshell?

It should also be noted at the back end, the prices in a securities market is made from limit orders. If somebody place a market order, what they get is the best limit order(s) available in the direction of the market they are addressing - the best sell order(s) if they are buying, and the best buy order(s) if they are selling.

At the securities market level, a limit order is active until it is explictly cancelled.