Stock market is like any other market where product get traded or exchange hands. Only difference stock has over other market is the product, i.e. shares of company which get traded. There are 2 major markets/exchanges in India, BSE and NSE. SEBI regulates all activities related to trading including corporate governance. One can apply for IPO or trade shares in secondary market. SENSEX and NIFTY gives indication of health of overall market by tracking top companies (SENSEX – 30 companies, NIFTY – 50 companies).