Thermodynamics has to do with different relationships with other forms between heat and and forms of energy. So basically it's a branch of different forms of energy. It is the thermal energy transferred to and from other types of energy which describes how it affect different matters. For one thing, thermal energy is due to its temperature, in a nutshell, it means the energy of moving molecules. There can be a fairly amount of molecules that can easily interact with each other and complicate things. This is where equilibrium comes in. Equilibrium defines when the system meets the standards. To get a better understanding, here are some examples of different heat sources.
Heat is converted between different substances because of the temperature difference between them. Heat cannot be created or destroyed, but it can be moved to different spots, while it can also be moved to and from other forms of energy. A steam turbine can be a good example. It can transfer heat to kinetic energy that runs a system and causes the kinetic energy to change into electrical energy.
Heat is responsible and is an important matter. Speed is a big role, because if the atoms and molecules move faster, the temperature rises higher and higher. The more atoms and molecules that are moving, means the greater amount of heat that is being converted. Measuring temperature means that we have to take smaller portions of what we are measuring. As for measuring in a larger portion, it wouldn't be accurate considering it takes up a large amount of space, there could possibly be a certain spot where the temperature is different.