Having a doorbell mounted next to your home's front door is a useful way for visitors to alert you to their presence. Whereas knocking may not be audible throughout the entire home, a the sound of a doorbell often is. The doorbell button mounted on the exterior of your home is connected to a bell inside, either through a wired system or via a wireless signal.
In nearly every home, the doorbell is located on the left or right side of the front door. The bell typically isn't on the trim surrounding the door, but rather on the wall next to the trim. In most cases, the doorbell is placed on the same side of the door as the handle, and opposite from the hinges. This way, a person who rings the doorbell is directly in front of the door when the resident opens it.
Doorbells are typically mounted between 40 and 44 inches off the ground so that they are easily accessible to visitors in a range of heights.
Doorbells are available in a variety of styles and are typically made of metal and plastic. Some doorbells contain a light that illuminates the doorbell button at night, making it visible to visitors.
If you live in an apartment building or condominium, you may have a door knocker on your door rather than a doorbell. Most communal buildings have an extensive doorbell system in the building's lobby. Here, visitors press a button that connects an intercom or phone in the lobby to an intercom or phone in your apartment. Visitors are still ringing your doorbell, in a sense, but they're not directly in front of your door.