Scale
A stepwise sequence of notes within the octave.
What it means
A scale arranges the note stock of a music in stepwise sequence within an octave. It is not music but an order: an overview of which notes are available and in what relation they stand to one another. Decisive here is not the number of notes alone but the distribution of the distances between them.
Musical use
Everything further follows from this distribution. If all steps are the same size — as in the whole-tone and the chromatic scale — no note stands out, and there is no centre. If they are unequally distributed, as in the diatonic scale with its five whole and two half steps, every degree gets its own character, and from this arises the pull on which cadence and tonality rest.
The scales in common use are numerous: major and the three forms of minor, the church modes, pentatonicism in its various forms, the blues scale, non-European orders such as the ragas and the basic scales of South Indian music. They differ in number of notes, in the distances between them, and in whether they run the same ascending and descending.
Bear in mind that scales are descriptions, not prescriptions: they summarize what a music uses and are derived from it, not the other way around. With ragas, for instance, the description as a scale clearly falls short.
As the basic material of melodic writing, scales underlie almost every music. Alongside major and minor, the church modes, pentatonicism, the whole-tone scale, and the chromatic scale are important.
Other names
In French the scale is called gamme, in Italian scala. Gamme goes back to the Greek letter gamma, with which the lowest note of the tone system was designated in the Middle Ages; scala literally means staircase or ladder.
Performance practice
Practise scales with a musical intention — for evenness of sound and length, with attention to the half-step positions, with a leading toward the root. Twenty thoughtless repetitions bring less than five attentive ones. Name the degrees as you practise; thinking in degrees is the basis for transposing, analysing, and improvising.