Gerald Appel invented the Moving Average Convergence/Divergence (MACD) indicator in the late 1970s. It is now one of the most widely available momentum indicators, as well as one of the most simple and effective. Moving averages are used by the MACD indicator, which converts them into a momentum oscillator by subtracting the longer moving average from the shorter one. The indicator also makes use of moving averages. Moving averages are a trend-following statistical measurement. As a result, the MACD can provide pattern following in addition to traction, representing the ideal combination of all possible benefits. As time passes, the moving averages will eventually converge, cross, and diverge, causing the MACD to oscillate above and below the zero axis.
The MACD is a representation of the difference between its signal lines. The Moving Average Convergence Divergence (MACD) is a popular and widely used technical analysis indicator that traders and analysts use to assess market momentum.

https://en.wikipedia.org/wiki/MACD