Stock trading takes place through the broker who helps in placing the order.If the trader anticipates the price to do up,he takes long position and if he takes short position he anticipates the price to fall down and get benefited.If the stocks are bought and sold within a day it is called as intraday,If it is kept for longer duration it is positional trading.Buyers and sellers determine stock price.If one party fails does not perform the obligations penalty is levied.Stock trading can be classified as gambling if the trader is taking more risks than the return and if it is vice versa it is business.