What is the significance of the tonic note in music theory and how does it influence the overall structure of a musical composition?

The tonic note is the main note in a musical key and serves as a point of rest and resolution. It provides a sense of stability and home base in a composition. The tonic note influences the overall structure of a musical composition by establishing the key and creating a framework for the other notes and chords to revolve around. It helps to create tension and release, leading to a satisfying and cohesive musical experience.