Stock Exchange
A stock exchange is an organization for bringing the buyers and sellers of stock and other financial instruments together. They offer a guarantee for the seller by clearing transactions at the end of the day. It allows companies to go public and gain some money, which can be used for investment and developement.
The most important exchanges around the world are the american NASDAQ and the New York Stock Exchange (NYSE) which had recently merged with Euronext creating the first global stock exchange(NYSE Euronext).