What is defined as a half tone, such as moving from G to Ab on a keyboard?

A semitone is defined as the smallest interval in Western music, equivalent to a half tone. When you move from one note to an adjacent note, such as from G to Ab on a keyboard, you are moving by one semitone. This concept is fundamental in music theory, as it forms the basis for constructing scales and understanding pitch relationships.

In a musical context, the semitone is essential for understanding the structure of scales, chords, and melodies. Each semitone represents a step on the keyboard, and this small interval plays a crucial role in creating tension and resolution in music.

In contrast, a whole tone represents two semitones, an octave encompasses eight notes or twelve semitones, and a quarter tone refers to an interval smaller than a semitone, applicable in microtonal music. These concepts build upon the basic understanding of semitones, but they do not fit the definition of a half tone.