Law students have long complained that they have to learn to split hairs. It is undeniable that distinctions abound in American law. There are distinctions to be learned in every area of law, and evidence law is no exception. In some cases, the evidentiary distinction is set out explicitly on the face of a statute, such as a provision of the Federal Rules of Evidence. In other cases, the courts read the statutory language of the Federal Rules in light of distinctions of common law origin. In evidence, the student has to focus on the distinctions to a greater degree than in other courses. Thus, this short text refines the reader's understanding of the most important evidentiary distinctions. The structure of this text parallels the organization of the Federal Rules. For each distinction, the text states the distinction, describes its general importance, and gives specific examples.