A time series plot is a graph that you can use to evaluate patterns and behavior in data over time. A time series plot displays observations on the y-axis against equally spaced time intervals on the x-axis.
Time series plots are often used to examine daily, weekly, seasonal or annual variations, or before-and-after effects of a process change. Time series plots are especially useful for comparing data patterns of different groups. For example, you could examine monthly production for several plants for the previous year, or employment trends in different industries across several months.