Stock prices up and down depending on supply and demand. When there is a great demand for the stock, and its price rises. Since there are more interested buyers than sellers, and will increase the share price. When there is a number of sellers than buyers, the price will decline.
The share price reflects the opinion of the investment community in stock. The price is not necessarily the true value of the company. This means that short-term price is often affected people's feelings rather than facts. Price can be moved on the basis of information, misinformation and rumors.
Your goal as an investor to buy a stock company that will increase in value over time shares. If the issuing company grow its sales and earnings growth, investors can buy more shares. If the share price has risen, you can sell their shares for a profit.
For example, imagine that you buy 100 shares at $ 15 each. This is an investment of $ 1,500. Two years later, the higher the price to $ 20 now, your investment is worth $ 2,000. If you sell your shares, you will recognize a gain $ 500 before fees and commissions ($ 2,000 - $ 1,500).