How is a system defined in thermodynamics?

In thermodynamics, a system is defined as the specific part of the universe that is being studied or analyzed. It is essentially the area where we focus our attention and make measurements, while everything outside of this defined boundary is considered the surroundings. This allows scientists to isolate and study the properties, energy changes, and interactions that occur within the system without the complexities introduced by external factors.

When we refer to the system as the portion of interest, we can categorize systems into various types: closed, open, or isolated, depending on whether they exchange energy or matter with their surroundings. This definition is fundamental to thermodynamic analysis because it helps clarify which variables and parameters are relevant for solving problems related to heat, work, and energy transformations.