Futon beds are originally traditional beds that were used in Japan years ago and are still being used. It is part of their culture. A futon bed is basically a bedding that has a lot of fluff. It has padding that is extremely comfortable and anyone will like to lay on it.
Traditionally it had a padded mattress and quilted design. They were pliable and so could easily be carried and stored away when not required. Doing this served a great purpose of making the room look bigger and more functional during the day. Therefore, a bedroom could be used for other purposes besides sleeping too.
Now the definition of a futon bed has changed somehow. More than anything else it is part of the furniture that is comfortable to sit on and lay on. Now futon beds come in various shapes. The standard futon bed has a wooden structure underneath a quilt like mattress on it. These beds are very comfortable and at home you can lie on them all day.
Some come in smaller sizes and can only be used as a chair or at best.
If you are planning to invest in a futon bed, be careful of a few things. Buy a one that is good looking when compared to the rest of your room. Do not buy too big a bed if you have a small room. Similarly if the color scheme is light, go for a contrasting yellow or orange shade. The options are unlimited. Go explore!