Energy is the ability of an object to produce changes or transform itself or other objects. It exists in different forms including light, thermal, sound, kinetic, solar, chemical, and nuclear. Energy can change from one form to another through transformations and can pass from one object to another but cannot be created or destroyed. Renewable energy sources like solar, wind, and hydraulic are naturally replenished, while non-renewable sources like coal, petroleum, natural gas, and uranium are limited.