While stainless steel is known for its resistance to rust, it is not completely immune to corrosion. There are several reasons why stainless steel can still rust. First, surface contamination such as dirt, dust and chemicals can damage the protective oxide layer and expose the steel to corrosion. It is important to regularly clean stainless steel surfaces to remove contaminants that can cause rust. Second, if stainless steel comes into contact with other metals, especially if it is wet, it will still corrode.