ACF

ACF, or Autocorrelation Function, measures how a data series relates to itself over different time intervals. It helps identify patterns, such as repeating cycles or trends, by comparing past values with future values at various time lags. Essentially, ACF reveals whether and how strongly data points are connected over time, aiding in understanding the underlying structure of time series data. It is commonly used in fields like finance, economics, and engineering to analyze the persistence or periodicity within a dataset.