Similar to the various markets we come across in our daily life like fish market, vegetable market, etc, stock market is a market that enables trading of stocks.It helps to identify buyer and seller for any given stock.
A company can go directly to the public to raise the capital. This is known as IPO, where in the investors can directly approach the company to buy the shares. Once done, the next trading of stocks takes pace in the secondary market without involving the company. The share holders can be given bonus, dividends, split shares based on the company decision.
The stock market sentiments are reflected through the sensex, which reflects the average of top 30 companies traded for the day.