General order book and matching engine

Millions of investors and traders make up the total market, all of whom may have various opinions on the worth of a particular stock and, as a result, the price at which they are willing to purchase or sell it. Over the course of a trading day, the thousands of transactions that occur when these investors and traders transform their intentions into actions by buying and/or selling a stock generate minute-by-minute gyrations in it.

A stock exchange provides a platform for this type of trading by connecting buyers and sellers of equities. A stockbroker is required for the typical person to have access to these markets. This stockbroker serves as a go-between for the buyer and the seller.

Initially, matching buyers and sellers of stocks on an exchange was done manually, but computerized trading systems are now being used more frequently. The open outcry system, in which dealers utilized verbal and hand-signal communication to purchase and sell...