Enthalpy refers to the total energy of all types in a thermodynamic system. Enthalpy cannot be measured directly so its quantification is typically related to the amount of energy either surrendered or absorbed by a system during a process or reaction.
An exothermic process is a process that releases energy into its system, reducing an object’s internal energy. Examples of exothermic processes include the condensation of rain or dew from water vapor, the hydration (curing) of cement, and the rapid oxidation (combustion) of fuels.
An endothermic process is a process that absorbs energy from an object’s system, increasing its internal energy. Examples of endothermic processes include the melting of an ice cube, the evaporation of water, and cooking (e.g. boiling, baking, grilling, and microwaving).
All phase changes involve either exothermic or endothermic reactions.
This video (3:52) explores the concept of enthalpy and state changes in thermography.