This document provides an introduction to CubeSats for first-time developers. It discusses the basics of CubeSats, including standard CubeSat sizes and dispenser systems used to deploy them from launch vehicles. It then gives an overview of the multi-step development process for a CubeSat project, from initial concept through launch and operations. Finally, it introduces some common mission models and requirements sources that CubeSat developers must consider to successfully design, build, test, launch and operate their small satellites. The goal is to lay out everything needed to take a CubeSat idea from concept to becoming an actual spacecraft in orbit.