This document presents the rule-consequent ontological definitions of fields and particles within Energy-Efficiency Theory (EET). It does not replace quantum field theory but provides an energy-ontological interpretation: a field is a continuous distribution of free-state energy; a particle is a localized steady-state structure of constrained-state energy. Mass is the integrated constrained-state energy density: m = E_c/c^2. This framework is intended as an internal foundation for the EET academic network, establishing the microscopic basis for wave-particle duality, condensed matter, phase transitions, and gravity. No empirical predictions are made; this is a rule-consequent document.