Carbon and oxygen combine to form carbon dioxide (CO2). This is a colorless, odorless gas that is a major component of the Earth's atmosphere.

Here's how it happens:

* Combustion: When fuels like wood or fossil fuels burn, carbon reacts with oxygen in the air to produce carbon dioxide.

* Respiration: Living organisms, including humans, breathe in oxygen and release carbon dioxide as a byproduct of cellular respiration.

* Decomposition: When organic matter breaks down, microorganisms release carbon dioxide into the atmosphere.

Carbon dioxide plays a crucial role in the Earth's climate system, acting as a greenhouse gas that traps heat.