Scale degrees can refer to notes within a scale or chords within a key. They are numbers which describe how far a note is from the root note of the scale or chord. They also relate how far a chord is from the key center.

There are many Jazz songs which are called "standards" because they are so well known. These songs were the popular songs of their day and have been played so many times that they are often transposed into various keys, usually to suit the vocalist's voice or to assist brass players in the case of instrumentals. As an aid to transposing, Jazz standards are often notated in scale degrees.

Scale degrees are written as Roman Numerals. For example, in the Key of C the C chord is I and the F chord is IV.

The tonality of the diatonic chords in a major key are:

I Major
II Minor
III Minor
IV Major
V Major
VI Minor
VII Half diminished

There are differences between all of these major and minor chords. These differences are found in the other chord tones. There are even more notes to draw from when you look at the scale tones which belong to each mode.