A greenhouse is a sheltered place in which tender plants are grown.

The greenhouse is made of glass or plastic and designed to let the light in. The glass and plastic also protect tender plants against frost.

The greenhouse is most important for trapping warmth. Sunlight passes through the glass and warms up the the plants and soil. These, in turn, warm the air inside by contact (the sunlight does not directly warm the air). However, the heat cannot get out easily and so it builds up, making the greenhouse warm without having to heat it using fuels. This is called the 'Greenhouse Effect'.

The video below shows how a greenhouse is used for protecting plants as they are potted on.