Disclosed is a method of swiftly identifying by touch or sight (including in low light) different keys in a set. Different keys are tagged with protrusions from their surface, and identifiers for different keys may differ in the total number of protrusions (which can vary in arrangement patterns in accordance with the number of protrusions), the shapes of the protrusions, and/or the color of the protrusions. The protrusions are fluorescent to allow identification in low light or dark. The set of protrusions for each key can be adhered to the key by placing them on one side of a support strip, which is coated with adhesive on the other side.