Moving Average (MA) is a popular technical analysis tool used to identify trends and determine momentum in the stock market. MA is the average of a stock's price over a specified period of time, and it is used to smooth out the short-term fluctuations in price data and provide traders with a clearer picture of the direction of the trend.

MA is calculated by adding the closing prices of a stock for a set number of periods and dividing the sum by the number of periods. For example, a simple moving average (SMA) of a stock's price over the last five days would be calculated by adding the closing prices of the stock for the past five days and dividing the result by five.

The formula for calculating the SMA is as follows:

SMA = (P1 + P2 + P3 + ... + Pn) / n

Where:

P1 is the closing price of the first period.
P2 is the closing price of the second period.
Pn is the closing price of the nth period.
n is the number of periods used in the calculation.

Traders use the MA to identify support and resistance levels, as well as to determine when to buy or sell a stock. When the stock's price crosses above the MA, it may be a signal to buy, and when the price crosses below the MA, it may be a signal to sell.

There are many variations of MA, including Simple Moving Average (SMA), Exponential Moving Average (EMA), and Weighted Moving Average (WMA). Each variation has its own unique formula and is used by traders depending on their needs and preferences.