What do you need to know about prime numbers, combinatorics, and the underpinnings of public key cryptography? Well, maybe more than you think! In this talk, we'll explore the branch of mathematics that deals with individual, countable things. Most of the math we learn in school deals with real-valued quantities like mass, length, and time. However, much of the work of the software developer deals with counting, combinations, numbers, graphs, and logical statements: the purview of discrete mathematics. Join us for this brief exploration of an often-overlooked but eminently practical area of mathematics.