A greenhouse (also called a glasshouse or hothouse)'s a building where plants are cultivated. A greenhouse's a structure with a glass or plastic roof and frequently glass or plastic walls; it heats up because incoming solar radiation from the sun warms plants, soil, and other things inside the building faster than heat can escape the structure. Air warmed by the heat from hot interior surfaces's retained in the building by the roof and wall. These structures range in size from small sheds to ve… (More on Greenhouse)