Starbucks Red Cup Day has become an unofficial harbinger of the holiday season for fans of the coffee chain. Here's a look at what makes Red Cup Day special.

Customers who return to Starbucks with the custom cup, or any reusable cup, will receive a 10-cent discount on their order and Starbucks Rewards members can earn 25 stars when they bring back their reusable red cup for future orders.

Thursday is Red Cup Day at Starbucks, one of the most anticipated days of the year for Starbucks fanatics. The coffee chain rewards customers who order select holiday beverages with a free limited-edition red holiday cup.