What is Stock Exchange?

Stock exchanges are markets where the participants come together for buying and selling of financial instruments such as shares, debentures, bonds, etc. it is run by set rules and regulations set by appropriate bodies such as SEBI in India.  Only the securities of listed companies are traded with stock exchanges. All such stock exchanges shall be recognized by the government and only registered brokers and members are allowed to trade instruments on it.  
There are around 9 official Stock Exchanges in India-

1. Bombay Stock Exchange (BSE)  
2. National Stock Exchange of India (NSE)  
3. Calcutta Stock Exchange 
4. India International Exchange (India INX)  
5. Indian Commodity Exchange (ICEX) 
6. Metropolitan Stock Exchange of India Ltd. (MSE)  
7. Multi Commodity Exchange of India Ltd. (MCX)  
8. National Commodity & Derivatives Exchange Ltd. (NCDEX)  
9. NSE IFSC Ltd. (NSE International Exchange)