Year-over-year (YOY) is the comparison of one period with the same period from the previous year(s). YOY growth compares how much you’ve grown in the recent period compared to the past period(s). The period is typically a month or quarter (e.g., fourth quarter of 2020 compared to fourth quarter of 2019). [1]
[1] Retrieved May 21, 2021, from https://www.patriotsoftware.com/blog/accounting/year-year-growth-calculate/