Carbon dioxide is an inorganic chemical compound with a wide range of commercial uses, from the production of lasers to the carbonation of soft drinks. This compound exists naturally from the Earth's environment, and it is produced in a variety of ways; commercial carbon dioxide is usually derived from the byproducts of industrial processes. This humble gas has become a topic of interest for humans because it is classified among the greenhouse gases, gases which impact the Earth's environment when they reach high concentrations in the atmosphere.

The chemical formula for carbon dioxide is CO2, and it takes the form of two oxygen molecules covalently bonded to a single carbon molecule. This compound is produced through decomposition of organic materials as well as through respiration and combustion. Amounts of carbon dioxide in the environment prior to the advent of the 20th century were kept stable by plants, which were capable of absorbing carbon dioxide as it was produced for use in photosynthesis.

As early as the 1600s, people were beginning to think about carbon dioxide, although they didn't know what to call it. Flemish chemist Jan Baptist van Helmont made observations which hinted at the existence of carbon dioxide, setting the stage for breakthrough work in the 18th century by Joseph Black, a Scottish chemist who identified carbon dioxide and explored many of its properties. By the 1800s, people had succeeded in creating and studying other forms of carbon dioxide, such as its solid form.

At room temperature, carbon dioxide takes the form of an odorless, colorless gas which is incombustible in normal conditions. Carbon dioxide can be forced into a solid form, in which case it is known as dry ice, and the gas is toxic to animals in high concentrations. People who inhale too much carbon dioxide essentially suffocate, ultimately falling into unconsciousness as their oxygen saturation level drops.

This gas is used for things like creating an inert environment for welding, fire suppression, and the carbonation of beverages, among many other things. Carbon dioxide is an important part of the carbon cycle, a complex cycle which is behind many of the mechanics of life on Earth. While this gas is entirely natural, some people began to be concerned about rising carbon dioxide levels towards the end of the 20th century. Scientists became concerned that humans were producing too much carbon dioxide for plants to process, a practice which could potentially lead to serious environmental problems.