They are orders based on what kind of price you are expecting your trade to be executed at. You can place such orders based on your view of the market. Let us understand further.
Limit Price/Order – An order that allows the price to be specified while entering the order into the system. If you place a limit order while buying, then the system will execute the order at the price or below that price. When you place a limit sell order then the system will execute at or above the said price only. That is why many limit orders do not get executed. Such limit orders are useful in volatile markets where you can afford to wait for the right level rather than trying to ride the market trend.
Market Price/Order – An order to buy or sell securities at the best price obtainable at the time of entering the order. A market order is useful if you are buying in a falling market or if you are selling in a rising market. You can place a phased market order in such cases to make the best of the price movement in your favor.