Using simple moving average in Equity
A shorter term MA would be used for short term changes in price whilst a long term MA would be used for longer term movements in price.  A 200 day SMA is widely used to determine the trend of the stock, simply a cross above the 200 day SMA would mean the stock may be entering an uptrend and a cross below that the price may be entering a downtrend. If the price is continuosly going above and below in a short period of time it is usually range trading. Then there are EMAs (Expodential Moving Averages) and WMAs (weighted moving averages) which give more emphasis to the latest price data than the earlier price data in the period chosen compared to a SMA. MAs can be used in many different ways, too many to list all here. The best way to learn about them is to read some TA books and articles about them, then choose a couple of strategies where you can use them in combination with a couple of other indicators that are complimentary with each other.