Argon and helium are both gases that are found in the Earth's atmosphere. Argon is a noble GAS with the chemical symbol Ar, while helium is a colorless, odorless, tasteless, non-toxic, inert GAS with the chemical symbol He. Both gases are used in a variety of applications, including welding, lighting, and medical imaging. Argon is also used in the production of semiconductors and lasers, while helium is used in cryogenics and rocket fuel.