A coupon train is a collaborative effort among a group of individuals to share and exchange coupons in order to maximize savings on purchases. This train typically starts with one person who collects and organizes a variety of coupons, and then passes them on to the next person in the train. Each person adds their own coupons to the collection before passing it on to the next person, creating a continuous loop of coupon sharing. This allows participants to access a wider range of coupons and potentially save more money on their purchases. The concept of a coupon train promotes community and teamwork, as well as smart and strategic shopping.