Scale: a sequence of musical notes in ascending or descending order
- Major scale: a pattern built of the whole and half steps of consecutive white notes of the keyboard from C to the next C. The pattern can be applied to any starting pitch.
- Minor scale: a pattern built of the whole and half steps of consecutive white notes of the keyboard from A to the next A. The pattern can be applied to any starting pitch.
- Chromatic scale: a pattern of rising or falling semitones
- Whole tone scale: a pattern of rising or falling whole tones
- Pentatonic scale: a five-note pattern built of the two-semitone or three-semitone steps of consecutive black notes on a keyboard from C# to C#. The pattern can be applied to any starting pitch.
- Octatonic scale: an eight-note pattern built of alternating whole steps and half steps
- Modes: scale patterns of whole steps and half steps, which include but are not restricted to major and minor scales
Key: a scale or series of notes and triads or other chords determined by the pattern of the mode (major/minor) and by
the first note (tonic or key note) of a scale. Each key is named for its tonic. (E major or d minor, e.g.)
Modulation: a series of chords that establish a new key
Harmonic Hierarchy: Triads within a key have different weights, functions, frequency of use, levels of tension, and importance, depending on their root note:
Tonic triad: built on scale degree 1, home plate, most important
Dominant: scale degree 5, most common destination, with the most tension
Subdominant: scale degree 4, slightly weaker destination: (but is also equally far from the tonic if you head down the scale as the dominant is heading up the scale, and therefore balances the dominant)
Both Dominant and Subdominant pull toward the tonic.
Mediant: scale degree 3, and Submediant: scale degree 6, help clarify the mode (major or minor), they are also equidistant from the tonic, and balance each other.
Supertonic: scale degree 2, serves as a much weaker substitute for either Dominant or Subdominant
Leading tone: scale degree 7, melodically pulls very strongly toward the tonic, and harmonically serves as a substitute for the dominant.
There are many other chords, consisting of variations, alterations, and additions to these basic triads. The most common are seventh chords, which add a fourth note to a triad.
(for more information on chords, click on "Intervals and chords" - the sixth item in the upper left sidebar.)