A Harmonic Oscillator is an integral part of periodic motion in Classical and Quantum Theory. For systems with small fluctuations near stable points of equilibrium, the Harmonic Oscillator serves as a good approximation for measuring eigenstates and wave amplitudes of the particle(s). Aside from the classical version, this presentation will include the Lie Algebra of commutation relations as well as the ladder operators (Discrete and Continuous) as it pertains to a Quantum Harmonic Oscillator. After that, one of its\u27 contributions to scalar fields in Quantum Field Theory, namely the Casimir Force, will be discussed. Whether it is a system of one oscillator or a system of decoupled oscillators, this concept could be applied to the fields ...