We attempt to give an intuitive notion of a quantum field theory by considering one of the most simple examples - the free boson. We introduce it by considering its prior historical incarnations - the classical harmonic oscillator, the 1-D wave equation, quantum harmonic oscillator, and finally the free boson quantum field itself. Our aim is to explain how all these objects are fundamentally the same structure developed in different setting. Along the way we highlight some connection to probability theory, random walks and Gaussian free fields. If time permits, we mention other examples beyond free boson and vertex algebras. No background is assumed.