Commission prices are the key advantage of online discount brokers. Consider that a popular full-service brokerage firm charges a minimum of $50 just to buy or sell stock. The commission is variable, so the larger the order, the larger the commission. To buy or sell $10,000 of stock, a client would pay $80. On a $25,000 order, the commission surges to $205 -- and commissions for funds can be even higher.
The idea of perception is important, especially in investing. As you gain more knowledge about investments – for example, how stocks are bought and sold, how much volatility (price change) is usually present, and the difficulty or ease of liquidating an investment – you are likely to consider stock investments to have less risk than you thought before making your first purchase. As a consequence, your anxiety when investing is less intense, even though your risk tolerance remains unchanged because your perception of the risk has evolved.

This education really ought to include one of the daily papers that covers the movements on the stock exchange (information here) in detail, such as the Financial Times or Wall Street Journal. Remember, the investment bankers that you are competing against have Bloomberg terminals and Reuters subscriptions, while everyone else is watching CNN and MSNBC. Since everyone is reading the same things on the same days, these might not be the best places to pick up your share market tips...
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.