All protectable marks are source-identifying, or distinctive. Trademark law recognizes a range of distinctiveness. It’s best to think of this range as a spectrum of color instead of discrete, categorical buckets. A mark’s relative strength, or distinctiveness, impacts what a trademark owner must prove to federally register and enforce its rights. At one end of the spectrum, owners of stronger, inherently distinctive marks don’t need to prove secondary meaning. At the other end of the...