internal energy

This term is a technical concept used primarily in thermodynamics and physics. It refers to the energy stored within a system at a microscopic level, meaning it is independent of the system's macroscopic motion or position in an external field. It is a state function, meaning its value depends only on the current state of the system, not on how the system reached that state.

In practical application, internal energy is typically discussed in the context of the First Law of Thermodynamics, where it is related to heat transfer and work performed. Because it represents a sum of microscopic energies, it is generally impossible to measure the absolute value of internal energy; instead, scientists measure the change in internal energy during a process.