Stainless steel alloys contain carbon, chromium, nickel, molybdenum, and manganese, phosphorus, sulfur, and silicon as trace elements.
The most common alloys (e.g. 304 and 304L (S30400 and S30403)) are sometimes called 18-8 or 18% chromium and 8% nickel because that is their basic composition. Types 304 and 316 are the most commonly used stainless steels
Unlike ordinary steel, stainless steel isn't prone to corrosion, rusting, or staining with exposure to water. But this isn't to say it's completely stain-proof. In areas with low oxygen, high salinity, or poor air circulation, stainless steel is vulnerable to staining.