See how a running total differs from a rate of change, using parcel deliveries...

https://iris-wiki.win/index.php/How_Do_I_Go_from_a_Rainfall_Rate_Graph_to_Total_Rainfall%3F

See how a running total differs from a rate of change, using parcel deliveries as an example. The article shows what each number means, why units matter, and how a daily rate over one week can tell a different story from the week’s total at work.