An octave, in musical terms, refers to the interval between two musical notes, where the higher note has a frequency that is double the lower note’s frequency.
This musical distance between notes is considered to be the most fundamental building block of melody and harmony in Western music.
To further clarify, the interval between the first and eighth notes of a major or minor scale is also an octave. In the key of C, for instance, there is a C as the first note and a C as the eighth note, both an octave above the first. All major and minor keys follow this pattern to the same extent.
The octave is frequently divided into twelve equal parts called semitones in music theory, with each semitone representing the distance between two consecutive keys on a piano. This equal division of the octave allows for the development of a standardized system of tuning and playing instruments, allowing musicians to collaborate in a variety of keys and scales.
The concept of the octave is not limited to Western music and is found in many different musical traditions and cultures around the world. However, the specific way in which the octave is divided and used in music may vary from one tradition to another.