When is a reaction designated as exergonic rather than endergonic?

A reaction is designated as exergonic when it releases energy, typically in the form of free energy, during the process. This is characterized by a negative change in Gibbs free energy (ΔG < 0), indicating that the products have less free energy than the reactants. In contrast, an endergonic reaction requires an input of energy, resulting in a positive change in Gibbs free energy (ΔG > 0).