This chapter explains basic energy concepts, defining the constructs of material, cognitive, or affective energy. Material energy represents physical potential that can be sensed and used, cognitive energy encompasses mental potential that can be used but not sensed, and affective energy reflects emotional potential that can be felt but neither sensed nor directly used. The chapter explores how these energy types interact within and between unities (entities), introducing the concepts of Usable Energy State (UES) and Overall Energy State (OES). It examines how energy can be categorised as activated, passive, or reserved, and discusses the role of Anticipated Energy Exchange (ANEE). Drawing from various disciplines, the chapter establishes foundational definitions and relationships that help explain how we manage and deploy different forms of energy in our work. While the framework is primarily conceptual, it provides a structured approach to understanding the complex interplay between physical, mental, and emotional aspects of practice. This understanding is essential for effective energy management and personal development in modern work environments.