A door hanger (also spelled doorhanger or door-hanger) is a plastic or cardboard sign, generally rectangular in shape, cut to hang from the handle or knob of a door. They are sometimes used to distribute print advertising to residences. Door hangers are often seen in hotels and other places of lodging as a means for guests to communicate with maintenance and housekeeping staff.
One common place where do not disturb signs are used is in places of lodging, where guests can place these signs on the door in order to inform staff, including housekeeping, to respect their privacy. Some hotels also provide "make up room" signs giving the opposite instructions.
They are also used in schools to let other staff members and students at the school know that testing is in progress in the particular classroom.
Do not disturb signs can also be used by those who keep valuables in their rooms in order to deter possible thieves.
In 2009, a do not disturb sign was blamed for concealing the disappearance of an elderly couple on a cruise ship.
Some hotels are using high tech means to replace paper do not disturb signs that hang on the door. One example is a privacy button that one can press from within the room to light up an indicator outside the room.
Door Hangers are also used in competition with direct mail as an advertising vehicle. Most recently, companies providing this type of advertising have been using the term Direct to Door Advertising. This type of advertising offers a number of advantages over traditional direct mail in that the impression is "guaranteed". The home owner must handle the piece and typically on a door hanger there is just one advertising message giving the advertiser great exposure. 
This type of advertising is used by national brands and local companies to help drive traffic into their stores, increase trial by offering a sample, and to increase their brand awareness. This method of delivery can often be more cost effective and with today's technology, the delivery of the pieces is completely trackable by integrating GPS and photos into the Proof of Performance. 
- Elliott, Christopher (June 29, 2008). "As hotels squeeze cleaning staff, guests get caught in the middle. How to make sure your housekeeping needs get met". San Francisco Chronicle. Retrieved 2 November 2010.
- Edward G. Hinkelman, Myron Manley, James L. Nolan, Karla C. Shippey, Wendy Bidwell, Alexandra Woznick. Importers manual USA. 4. p. 46. Retrieved 2 Nopvember 2010. Check date values in:
- Maurer, Kevin (2008-06-26). "Warrant: Body of pregnant soldier found in tub". USA Today. Retrieved 2 November 2010.
- "Hotel 'Do not Disturb' sign hid murder". Express.co.uk. Retrieved 2 November 2010.
- Riches, Chris (30 May 2009). "Hotel 'do not disturb' sign hid murder". Star Tribune. Retrieved 2 November 2010.
- "Elderly Couple Disappears On Cruise Ship". CBS News. January 17, 2009. Retrieved 2 November 2010.
- "From hotel rooms to hi-tech havens". The Sydney Morning Herald. May 9, 23008. Retrieved 2 November 2010. Check date values in:
- "Catching ZZZZZZZZs a sign of the times". tvnz.co.nz. 26 February 2005. Retrieved 2 November 2010.
- Kingsbury, Amanda (27 February 2005). "Genius works behind 'do not disturb' sign". projo.com. Retrieved 2 November 2010.
- "Make your own 'Do Not Disturb' sign". Associated Press. Retrieved 2 November 2010.
- "The disturbin results of Embassy Suites 'Do Not Disturb' sign". hotelchatter.com.