openFrameworks is a cross-platform programming toolkit and library to perform creative coding in C++. It contains all you need to efficiently implement real-time tasks, such as generating 2D and 3D graphics, processing video and sound, and using networking. openFrameworks Essentials is a guide that can be used for learning and using openFrameworks to develop creative and artistic real-time applications. It is a fast-paced tutorial that begins with installing openFrameworks, and then takes a step-by-step approach towards using openFrameworks to build a video synthesizer project. We will investigate and implement features such as 2D and 3D graphics, GUI, shaders, reaction on sound, the OSC networking protocol, and the Arduino. This book will empower you with the practical skills required to build creative apps and projects using openFrameworks.