Green Monday is one of the retail industry’s busiest shopping days, usually on the second Monday of December (this year December 9). Like other major retail shopping days like Prime Day, Black Friday, and Cyber Monday, it encourages people to shop online, buy last-minute Christmas gifts and take advantage of great deals.

Many people confuse it for an environmentally friendly holiday, but it actually marks the best day for online sales in December. The term was coined by eBay’s Shopping.com in 2007. “Green” refers to the money retailers make that day.

Many retail stores including Amazon, Target, and Walmart offer Green Monday deals. It has become more and more popular over the years with many websites also offering deals and discounts.

After Cyber Monday, Green Monday has grown to be the second biggest online shopping holiday, and spending has increased every year, with it now reaching over $3 billion.