The symbol for krypton is Kr on the table of elements. The air contains krypton at about 1 part per million, and under normal conditions, it's a colorless and odorless gas. In solid form, krypton is a white crystalline substance with a cubic close-packed structure like most rare gases.
Sir William Ramsay and his student Morris Travers discovered krypton in 1898, when it was left as residue after they boiled liquid air. After boiling away water, oxygen, helium, nitrogen and argon, only krypton was left in the residue. As well as being present in the atmosphere, krypton is also obtained from the liquefaction and separation of air as a by-product. Krypton is stored at high pressure in cylinders, which are commercially available.