Energy is a quantity that describes the capacity to do work or cause change in a system. In physics, it can take many forms—kinetic energy from motion, potential energy from position, thermal energy from temperature, chemical energy in bonds, electrical energy from moving charges, and more—and these forms can be converted from one to another. A fundamental principle is the conservation of energy: in a closed system, energy is not created or destroyed, only transformed and redistributed among its components. Key ideas to understand energy:

• Forms of energy:
  • Mechanical (kinetic and potential)
  • Thermal (related to temperature)
  • Chemical (bonds in molecules)
  • Electrical (movement of charge)
  • Radiant/solar or electromagnetic (light and other waves)
  • Nuclear or mass-energy (binding energy inside atoms)
• Work and energy: When a force causes a displacement, work is done, and energy is transferred or transformed. The amount of work is the product of the force and the displacement in the direction of the force.
• Conservation: In any process, the total energy before equals the total energy after, accounting for all kinds of energy involved (including energy dissipated as heat or sound in real-world systems).
• Everyday relevance: Energy underpins almost every action—your body converts chemical energy from food into kinetic energy for movement, machines convert electrical or chemical energy into motion or heat, and the sun provides energy that drives weather, heat, and life on Earth.

If you’d like, I can tailor this further to a specific context (e.g., everyday examples, a physics classroom explanation, or a discussion of energy in engineering systems) and include simple equations to illustrate the concepts.