Amazon revenue chart?

If you look at this article and scroll down, there’s a chart of Amazon’s revenue vs. profit:

https://www.recode.net/2018/2/1/16961598/amazon-jeff-bezos-record-profit-11-quarter-q4-2017-earnings

Why does revenue growth show that consistent pattern of peaks and troughs within the overall upward trend? Is that usual for a business?

The peaks are 4th quarter each year - holiday shopping.

Ugh. So obvious, yet so obscure to me. Thanks.