Covalent Bonding: A type of chemical bond where electrons are shared between atoms. This is how the oxygen and carbon atoms are connected in CO2.
Greenhouse Gas: Gases in Earth's atmosphere that trap heat. They let sunlight pass through the atmosphere, but they prevent the heat that sunlight brings from leaving the atmosphere. CO2 is one such gas.
Photosynthesis: The process by which green plants and some other organisms use sunlight to synthesize foods with the help of CO2 and water.