Energy is defined as the ability to do work. It is categorized into two main types: potential and kinetic. Potential energy is the energy associated with the position, composition, or condition of an object. It is also known as the energy at rest or the stored energy. For example, a book on a table possesses potential energy due to its height above the ground. This potential energy remains stored in the book as long as it is held at that position. Kinetic energy is that which is associated with the motion of an object. For instance, when the book falls from the table, its potential energy gets converted into kinetic energy due to its motion.