Yahoo! Finance

  The Definition

A stock market is a  market for the trading of  company stock, and  derivatives of same; both of  these are securities listed on  a stock exchange as well as  those only traded privately.
The term 'the stock market' is a concept for the mechanism that enables the trading of company stocks (collective shares), other securities, and derivatives. Bonds are still traditionally traded in an informal, over-the-counter market known as the bond market. Commodities are traded in commodities markets, and derivatives are traded in a variety of markets (but, like bonds, mostly 'over-the-counter').
The size of the worldwide 'bond market' is estimated at $45 trillion. The size of the 'stock market' is estimated at about $51 trillion. 

Chicago Stock Exchange

 Trading

Participants in the stock market range from small individual stock investors to large hedge fund traders, who can be based anywhere. Their orders usually end up with a professional at a stock exchange, who executes the order.
Actual trades are based on an auction market paradigm where a potential buyer bids a specific price for a stock and a potential seller asks a specific price for the stock. (Buying or selling at market means you will accept any bid price or ask price for the stock.) When the bid and ask prices match, a sale takes place on a first come first served basis if there are multiple bidders or askers at a given price.
The purpose of a stock exchange is to facilitate the exchange of securities between buyers and sellers, thus providing a marketplace (virtual or real). 

Bombay Stock Exchange - India

 The stock market is one of the most important sources for companies to raise money. This allows businesses to go public, or raise additional capital for expansion. The liquidity that an exchange provides affords investors the ability to quickly and easily sell securities. This is an attractive feature of investing in stocks, compared to other less liquid investments such as real estate.
History has shown that the price of shares and other assets is an important part of the dynamics of economic activity, and can influence or be an indicator of social mood. 

Hong Kong Exchanges

 Investment strategies

One of the many things people always want to know about the stock market is, "How do I make money investing?" There are many different approaches; two basic methods are classified as either fundamental analysis or technical analysis. Fundamental analysis refers to analyzing companies by their financial statements found in SEC Filings, business trends, general economic conditions, etc.
Technical analysis studies price actions in markets through the use of charts and quantitative techniques to attempt to forecast price trends regardless of the company's financial prospects.  

Stock Exchange
of Singapore

 Individual investors, and financial risk

Riskier long-term saving requires that an individual possess the ability to manage the associated increased risks. Stock prices fluctuate widely, in marked contrast to the stability of (government insured) bank deposits or bonds. This is something that could affect not only the individual investor or household, but also the economy on a large scale. The following deals with some of the risks of the financial sector in general and the stock market in particular. This is certainly more important now that so many newcomers have entered the stock market, or have acquired other 'risky' investments (such as 'investment' property, i.e., real estate and collectables).