Greenhouse gases are:

The greenhouse is a structure having a transparent roof and sidewalls which helps in providing a regulated environment for growth of plants in cold climate. These structures, generally made of glass, trap heat within the walls to raise the internal temperature suitable for plant growth. Similarly, the gases in the atmosphere which help in trapping the heat rays reflected back from the Earth's surface are commonly called greenhouse gases. Carbon dioxide, methane, water vapour, etc. are classical examples of greenhouse gas that absorb the long wave radiations from the earth and help in keeping it warm.