YoY — compare with the same quarter last year

YoY (Year-over-Year) compares this quarter with the same quarter last year — not the previous quarter. Why? Seasons! A firecracker company sells most around Diwali. Comparing its Diwali quarter to its summer quarter is unfair — compare Diwali to last Diwali. Steadily growing YoY revenue and profit is one of the strongest signs of a healthy company.