A Greenhouse is a structure with walls and roof made of transparent material, such as glass and poly. Greenhouses are used to grow plants and tropical flowers and fruits, Gases in the atmosphere such as CO2, trap heat similar to the glass roof of a greenhouse. These heat trapping gases are called Greenhouse gases. The interior of greenhouse exposed to sunlight becomes significantly warmer than the external temperature protecting its contents in cold weather. The purpose of a Greenhouse is to magnify the light of the sun while protecting plants from freezing temperature.