First-order Transition

A first-order transition is a sudden change in a system's state, such as water turning into ice or boiling into steam. These transitions involve an abrupt shift accompanied by a release or absorption of energy (like heat) and often involve a change in structure or density. Unlike gradual changes, first-order transitions occur at specific conditions (temperature, pressure) and include processes like melting, freezing, or condensation. They are characterized by a clear boundary between phases, making them distinctly different states of matter.