Heat is a form of energy transferred from one place to another. Heat is simply the transfer of energy from a hot object to a colder object, In a body or thermodynamic system to another place, or beyond the boundary of one system to another one due to thermal contact even when the systems are at different temperatures.
It is also often described as the process of transfer of energy between physical entities. In this description, it is an energy transfer to the body in any other way than due to work performed on the body.The heat energy of a substance is determined by how active its atoms and molecules are. A hot object is one whose atoms and molecules are excited and show rapid movement. A cooler object’s molecules and atoms will be less excited and show less movement. When these guys are in the excited state, they take up a lot of space because they’re moving around so fast. When the atoms and molecules settle down, or cool down, they take up less space. Heat is the energy an object has because of the movement of its atoms and molecules which are continuously jiggling and moving around, hitting each other and other objects. When we add energy to an object, its atoms and molecules move faster increasing its energy of motion or heat. Even objects which are very cold have some heat energy because their atoms are still moving.