Does the world really need another article about Pythagorean triples? Here is why we think so. The set of Pythagorean triples has a lot of interesting structure, which has intrigued both amateur and professional mathematicians. It is the topic of an extensive mathematical literature, almost all of which relies on an enumeration of primitive Pythagorean triples that has been known since ancient times. But it is not widely known that there is a different enumeration, based on two simple geometric parameters that we call the height and the excess. In this article, we will use these parameters to make some known results about Pythagorean triples more transparent. And we will use them to achieve a better understanding of one natural group structure on the set of primitive Pythagorean triples, and to discover another one.Recall that a Pythagorean triple (PT) is an ordered triple (a, b, c) of positive integers such that a 2 + b 2 = c 2 . When a and b are relatively prime, the triple is a primitive PT (PPT). Each PT is a positive integer multiple of a uniquely determined PPT.The height and excess parameters are shown in FIGURE 1. For a PT (a, b, c), the height h is just c − b, and the excess e is a + b − c. The term excess arises from the fact that e is simply the extra distance one must travel when going along the two legs instead of the hypotenuse. Not all combinations of h and e can occur in an integer-sided triangle. We will see that, for a given h, the possible values of e are exactly the integer multiples of a certain integer d. The integer d is called the increment, and it is related to h in a simple way: d is the smallest positive integer whose square is divisible by 2h. Since e is a multiple of d, we can write e = kd for a positive integer k. As will be verified in Theorem 1, associating k and h to (a, b, c) sets up a one-to-one correspondence of the PTs with the pairs of positive integers (k, h). For example, everybody's favorite PT (3,4,5) corresponds to the pair (1, 1), and (4, 3, 5) and (5, 12, 13) correspond to (1, 2) and (2, 1) respectively, while the nonprimitive PTs (48, 189, 195) and (459, 1260, 1341) correspond to (7, 6) and (21, 81). We call this correspondence the height-excess enumeration.In the rest of this article, we will see various uses of the height and excess parameters. The overarching goal is to find structure on the set of Pythagorean triples. To best understand a particular structure on the set of PTs, we need to view it with the c THE MATHEMATICAL ASSOCIATION OF AMERICA