A stock broker is required to register with SEBI and be a member of a recognized stock exchange in order to buy, sell, or deal in securities. They must abide by the rules and regulations of the exchange, pay fees, and address investor complaints. Registration requires application through a stock exchange, which forwards the application to SEBI. SEBI verifies eligibility requirements prior to granting registration. Registered stock brokers must follow capital adequacy norms, codes of conduct, and are subject to inspection and penalties for non-compliance. The National Stock Exchange was established to provide a nationwide trading facility and screen-based trading system for securities including equities, debt instruments, and derivatives.