All trades are made up of separate orders, that are used together to make a complete trade. All trades consist of at least two orders (one buy and one sell order), usually with one order to enter the trade, and one or more orders to exit the trade.
A single order is either a buy order or a sell order, and an order can be used either to enter a trade or to exit a trade. If a trade is entered with a buy order, then it will be exited with a sell order, and vice versa. For example, if a trader expected the market's price to go up, the simplest trade would consist of one buy order to enter the trade, and one sell order to exit the trade. Conversely, if a trader expected the market's price to go down, the simplest trade would consist of one sell order to enter the trade, and one buy order to exit the trade. If this last example seems backwards, see the shorting entry in the trading glossary for an explanation.
Traders have access to many different types of orders that they can use in various combinations to make their trades. The following explanations will explain each of the order types, and how these orders are used in trading. Note that many traders do not fully understand all of these order types, and they may seem slightly abstract at first, but their use will become clearer once you start to use them in your trading.
Market Orders (MKT)
Market orders are orders to buy or sell a contract at the current best price, whatever that price may be. In an active market, market orders will always get filled, but not necessarily at the exact price that the trader intended. For example, a trader might place a market order when the best price is 1.2954, but other orders might get filled first, and the trader's order might get filled at 1.2956 instead. Market orders are used when you definitely want your order to be processed, and are willing to risk getting a slightly different price.
Limit Orders (LMT)
Limit orders are orders to buy or sell a contract at a specific or better price. Limit orders may or may not get filled depending upon how the market is moving, but if they do get filled it will always be at the chosen price, or at a better price if there is one available. For example, if a trader placed a limit order with a price of 1.2954, the order would only get filled at 1.2954 or better, if it got filled at all. Limit orders are used when you want to make sure that you get a suitable price, and are willing to risk not being filled at all.
Stop Orders (STP)
Stop orders are similar to market orders, in that they are orders to buy or sell a contract at the best available price, but they are only processed if the market reaches a specific price. For example, if the market price is 1.2567, a trader might place a buy stop order with a price of 1.2572. If the market then trades at 1.2572 or above, the trader's stop order will be processed as a market order, and will then get filled at the current best price. Stop orders are processed as market orders, so if the stop (or trigger) price is reached, the order will always get filled, but not necessarily at the price that the trader intended. Stop orders will trigger if the market trades at or past the stop price, so for a buy order, the stop price must be above the current price, and for a sell order, the stop price must be below the current price.