The device is a simple one. It is mounted on the door with one of the arms fixed on the door frame. When the door is opened, the spring inside the box is exercised and when the force opening the door is removed, the door closes automatically.
Some minor adjustments are necessary to ensure perfect closure of the door and also the speed at which the door closes.
Some immediate advantages of the door closers are:
Keeps dust away as the door is closed automatically
Enhances audio insulation. Noises from outside do not enter home and vice-versa
Enhances privacy and security, especially for the front door of the home
The door closers are available in multiple shapes, sizes and colors. You may choose one which matches you door color. They should be available in leading hardware stores across India.
Some variations in the fitting are also common. For instance some door closers are mounted mid way on the door instead of the top and some are even mounted at the bottom. Typically door closers are available for hinged doors although you may get some types for sliding doors as well.