When we talk about “schedulers”, many of us default to thinking of tools like Kubernetes, Mesos, Nomad, or Swarm. But the abstract challenge of scheduling–determining what tasks to run when, with what resources–has spanned the history of computing itself. We’ll begin our journey in the 1950s, and discuss the scheduling problems encountered in early processor design, mainframe resource sharing, and operating system development. We’ll discuss how high-performance numeric computing advancements shaped their own flavor of schedulers, and how the advent of the Internet and high-scale web applications has led to the tools we know and love today.