The element with the symbol 'Ar' is argon. Argon is a colorless, odorless noble gas that makes up about 0.93% of Earth's atmosphere. It is non-reactive due to its stable electronic configuration, which means it does not readily form compounds with other elements. Argon is used in various applications, including the manufacturing of light bulbs, as a shielding gas in welding, and in the production of semiconductor materials. Due to its inert nature, argon is safe for use in environments where chemical reactions need to be minimized.