Stainless Knives refer to knives whose blades, and often handles, are made from stainless steel. To qualify as stainless, the steel must contain a minimum of 10.5% chromium, the key element that provides corrosion resistance. Renowned for their ability to resist rust and corrosion, stainless steel knives maintain their condition even in humid environments.

Categories of stainless steel used in knives include:

1. Austenitic Stainless Steel: Common in household kitchen knives, grades like 304 or 316 combine good corrosion resistance with sufficient toughness.

2. Martensitic Stainless Steel: With higher carbon content, these steels, after heat treatment, achieve greater hardness and wear resistance, suitable for knives requiring excellent edge retention, such as those used by professional chefs. 

3. Ferritic Stainless Steel: While less common in premium knives, ferritic stainless steels are still utilized in more economical knife production, providing basic corrosion resistance albeit with potentially less toughness and hardness than the previous two types.