Astute readers will realise that the above guidance is mainly taking different angles to help prepare for and guide decision making by the investor. The ability to confidently make decisions is vital for investment profits and long-term success. This pdf about the decision making models of Charlie Munger (business partner to Warren Buffett at Berkshire Hathaway - both are certified investment immortals) is almost certain to prove helpful.
A broker is simply a licensed person through whom you can buy and sell these stocks. When you use an online platform, it essentially acts as an online broker. If someone wants to buy any product, he can contact a brokerage service. They would place an order and let him know the market price of the product. If the investor is interested, they would include a commission for themselves and process the order forward. If the user wishes to buy stock, the broker would forward his order to a stock exchange, which would approximately take 3 days to complete including the money exchange between the broker and the investor.