A den is where a bear sleeps when it hibernates through the winter, or where a fox sleeps at night. A bedroom is where people sleep. A den is also the name of a specific room in a house. If you have a very large house with lots of rooms, one room might be a den, but smaller houses would not have a dedicated room that is a den. A den is characterized by being slightly cave-like, such as having dark walls (or darker than normal) and often no windows (or fewer windows than normal), and often having lots of wood, such as wood wainscoting on the walls. It often has a big desk. It commonly used as a room to do business in, or as an entertaining place to smoke cigars, or a room that has the walls covered with books like a home library. This room became popular in the 1950s in the United States as the room that is where dad hangs out and has his stuff, separate from the rest of the house which mom decorates. You would expect to see his hunting trophies there, or where he keeps his art that mom doesn't want to see (like taxidermy, or paintings of cars). It is often the grown-up room that kids are not allowed to enter because dad is busy doing business in that room.

To add to what Cherry said, a den can also be used as a home office, a home library, or just a room to relax in.

Hello Sophia , Den is from old English "denn" and it means a comfortable usually secluded room ,it is part of the house similar to the bedroom and about its size . Many houses turn their den into a bedroom, because of the size of the family , while Bedroom is a room furnished mainly with a bed and intended primarily for sleeping . :)