Your interviewer will likely ask you knowledge-based questions to understand how well you are able to explain concepts to others. Be prepared for questions like this one by practicing a few possibilities ahead of time. This question is asking about what makes stainless steel unique among steels, specifically in contrast with tool steel. Stainless steel is known for its resistance to rust or corrosion, and it is generally classified by having at least 11% of the element chromium (Cr) in its chemical composition. In contrast, tool steels are known for their hardness, or their ability to resist deformation. Like their name, tool steels are typically used to make tools, and are characterized by their carbon content, typically between 0.5% and 1.5% by weight.