Carbon dioxide is a gas that is produced when materials containing carbon burn. The carbon in the material joins with oxygen in the air to make carbon dioxide.

Carbon dioxide can also be made by our bodies as we 'burn' the food we eat. We release it from our bodies when we breathe out.

Plants need carbon dioxide to make their tissues. They take it in through their leaves and combine it with water using the energy in sunlight.

If carbon dioxide is made very cold it turns into a solid called dry ice. As the dry ice gets warm it turns back into a gas again and at the same time cools down water in the air, causing a mist to form. In this way, dry ice can be used to make temporary clouds and mist on a theatre stage.

Carbon dioxide is released when fossil fuels and wood are burned. It is the main gas that holds heat and so is the main cause of global warming.