A Bitcoin exchange is a digital market place where traders can buy and sell bitcoins using different fiat currencies or altcoins. A bitcoins currency exchange is an online platform that acts as an intermediary between buyers and sellers of crypto currency. Bitcoin exchange match buyers with sellers .Like a traditional stock exchange ,traders can opt to buy and sell bitcoins by in putting either a market order or a limit order.When a market order is selected the trader is authorized the exchange to trade his coins for the best available price in online market. With a limit order set the trader directs the exchange to trade coins for a price below the current. ask or below the current bid depending on whether buying or selling.