The MACD indicator is a momentum indicator that is used to gauge the strength and direction of a trend. The MACD indicator is calculated by subtracting the 26-period Exponential Moving Average (EMA) from the 12-period EMA. 

The MACD indicator is displayed as a histogram and a signal line. The histogram portion of the MACD indicator represents the difference between the MACD line and the signal line. The signal line is a 9-period EMA of the MACD line. 

The MACD indicator can be used to identify trend reversals, as well as to gauge the strength of a trend. The MACD indicator is considered to be bullish when the MACD line is above the signal line, and bearish when the MACD line is below the signal line. 

The MACD indicator is also used to generate buy and sell signals. A buy signal is generated when the MACD line crosses above the signal line, and a sell signal is generated when the MACD line crosses below the signal line. 

The MACD indicator can also be used to identify overbought and oversold conditions. An overbought condition is said to exist when the MACD line is above the signal line by more than 2 standard deviations, and an oversold condition is said to exist when the MACD line is below the signal line by more than 2 standard deviations.