What does "XL twin" mean for a bed?

A Twin XL bed is 39 inches by 80 inches versus the traditional twin bed which is 75 inches long. A Twin XL mattress is the same length as a queen or king sized bed.

A Twin XL bed is great for taller children or adults but can be cramped if trying to sleep two people or an adult and a child. Placing two twin XL mattresses together will result in a king-sized bed. While this may be a convenient solution to accommodate taller people, it can be challenging to find sheets, comforters, bedding or a foam topper (if desired) to fit a mattress this size. A twin XL mattress may be a good fit for a guest room.