What are Stock Exchanges? 
Stock exchanges are the physical locations where stocks are bought and sold. The over-the-counter (OTC) market refers to securities transactions that are conducted through dealers in stocks and bonds, rather than on the floor of an exchange.
Exchanges are located all over the world, with the most famous one being the New York Stock Exchange. The NYSE annually trades almost $12 trillion dollars worth of capital. Thousands of stocks are listed on this exchange.
The Securities and Exchange Commission (SEC) regulates stock trading and exchanges and makes laws and rules governing the securities industry. The National Association of Securities Dealers (NASD) administers additional regulations. The NASD makes and enforces rules for its members and enforces federal securities acts.