1. Notes and Alterations

There are 7 natural notes: C, D, E, F, G, A, B.
We can add alterations (♭ and ♯), which give us 12 different notes in total:

C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯, B   ← Using Sharps (♯)
C, D♭, D, E♭, E, F, G♭, G, A♭, A, B♭, B   ← Using Flats (♭)

Both lists contain the same 12 sounds; they are just written differently. This is called the Chromatic Scale.

2. Degrees and the tonic

When we create a piece of music, we choose one of these 12 notes to be the "home base", called the tonic (Degree 1). The tonic gives the scale its name (e.g., if the tonic is C, the scale can be C Major, C Minor, C Minor Blues,...).

The other notes in the scale are assigned a number, called a degree, based on their relationship to the tonic. This system is useful because any melody can be moved to a new starting note (a new tonic), and the pattern of degrees (the "shape" of the melody) stays the same, even though the actual notes change.

Here are the common names for the degrees:

1: Tonic - The home note, the most stable

♭2

2: Supertonic (a whole tone above the Tonic)

♭3: Mediant - A minor 3rd (♭3) defines a Minor Scale

3: Mediant - A major 3rd (♮3) defines a Major Scale

4: Subdominant (a whole tone below the Dominant)

♯4 =♭5: Tritone: often called the “Blue note” in Jazz and Blues

5: Dominant - The second most important note after the Tonic; it creates tension that wants to resolve back to the Tonic

♯5 =♭6: Submediant (a major 3rd below the octave Tonic)

6: Submediant (a minor 3rd below the octave Tonic)

♭7: Subtonic (a whole tone below the octave Tonic)

7: Leading Tone - Creates strong tension, feels like it must lead up to the Tonic

3. Intervals

An interval is the space between two notes = the space between two degrees.

4. Scales 

A scale is a specific selection of notes (degrees) from the 12 available, arranged in order. The pattern of intervals defines the type of scale.

The Chromatic Scale uses all 12 notes.

The Major Scale uses 7 notes with this specific pattern of intervals: Whole tone - Whole tone - Half tone - Whole tone - Whole tone - Whole tone - Half tone (W-W-H-W-W-W-H). 

Its degrees are: 1, 2, 3, 4, 5, 6, 7

1-W-2-W-3-H-4-W-5-W-6-W-7-H-8  ← Degrees and intervals (8 is the octave of 1)

C-W-D-W-E-H-F-W-G-W-A-W-B-H-C  ← Notes and intervals with C as tonic

5. Chords: Notes played together

A chord is when you play multiple notes from a scale at the same time.

Triad: A chord built from three notes (e.g., degrees 1, 3, and 5).
Tetrad: A chord built from four notes (e.g., degrees 1, 3, 5, and 7).

Chords are often built by stacking intervals of a third, but not always.

Tertian chords are built only with thirds (major thirds and/or minor thirds).

Non-tertian chords are built with other intervals, not just thirds.

Quartal chords are built using fourths instead of thirds. (perfect fourths, diminished fourths, and/or augmented fourths).

In short: You choose a tonic (1) to establish a key. You select degrees (notes) to form a scale. You combine notes from that scale to build chords.

This process of creating chords from a scale is called harmonization.

ARN-Music Apps give you a very immediate and visual approach to harmonization, which you can use on your instrument. Once you have the scale, chords and harmonization, the next step is to create chord progressions. In the ARN-Music Apps you will find a really important and pratical tool: the circle of fifths.