Summary: if you travel frequently, you will notice that the twin mattress size is more common than you first thought. Many budget hotel rooms also have them. Measuring in at 38 inches wide and 75 inches in length, this size is a bit too small for most adults.
For children, twins are really useful. You can use rails along the sides of the bed so they won’t roll off the side. Also, this size of bed can easily fit on a bunk which means you get more floor space. These mattresses are great in a smaller room.
While these are a smaller size, they are useful in many situations. You can put 2 twins side by side to make a bigger bed. To make a combined bed like this more comfortable, you can use separate comforters and/or a king size comforter. You can also use a memory foam topper across both beds to make it feel like big bed. Twins are generally wide enough for adults, but depending on the height of the adult, a twin might not have enough length to be used on a regular basis. A twin can be a great solution for a smaller room, or as a way to have a guest stay long enough to be comfortable, but not so comfortable that they want to stay forever.