Stainless steel, also known as inox or Corrosion Resistant (Stainless) Steel (CRES), is an alloy of iron that is resistant to rusting and corrosion.  It contains at least 10.5% chromium, usually nickel, and may also contain other elements, such as carbon, to obtain the desired properties.  Stainless steel's resistance to corrosion results from the chromium, which forms a passive film that can protect the material and self-heal in the presence of oxygen.

The alloy's properties, such as luster and resistance to corrosion, are useful in many applications.  Stainless steel can be rolled into sheets, plates, bars, wire, and tubing.  These can be used in cookware, cutlery, surgical instruments, major appliances, vehicles, construction material in large buildings, industrial equipment (e.g., in paper mills, chemical plants, water treatment), and storage tanks and tankers for chemicals and food products.

The biological cleanability of stainless steel is superior to both aluminium and copper, and comparable to glass.  Its cleanability, strength, and corrosion resistance have prompted the use of stainless steel in pharmaceutical and food processing plants.

Different types of stainless steel are labeled with an AISI three-digit number.  The ISO 15510 standard lists the chemical compositions of stainless steels of the specifications in existing ISO, ASTM, EN, JIS, and GB standards in a useful interchange table.