Subdominant in the context of "Tonic (music)"

A riff is a short, repeated motif or figure in the melody or accompaniment of a musical composition. Riffs are most often found in various genres of rock music (including punk and heavy metal music), as well as Latin, funk, and jazz, although classical music is also sometimes based on a riff, as in Ravel's Boléro. Riffs can be as simple as a tenor saxophone honking a simple, catchy rhythmic figure, or as complex as the riff-based variations in the head arrangements played by the Count Basie Orchestra.

David Brackett (1999) defines riffs as "short melodic phrases", while Richard Middleton (1999) defines them as "short rhythmic, melodic, or harmonic figures repeated to form a structural framework". Author Rikky Rooksby states: "A riff is a short, repeated, memorable musical phrase, often pitched low on the guitar, which focuses much of the energy and excitement of a rock song."

In music theory, a dominant seventh chord, or major minor seventh chord, is a seventh chord composed of a root, major third, perfect fifth, and minor seventh; thus it is a major triad together with a minor seventh. It is often denoted by the letter name of the chord root and a superscript "7". In most cases, dominant seventh chord are built on the fifth degree of the major scale. An example is the dominant seventh chord built on G, written as G, having pitches G–B–D–F:

The leading note and the subdominant note combined form a diminished fifth, also known as a tritone. The clashing sound produced by playing these two notes together gives the dominant seventh chord its dissonant quality (i.e. its harmonic instability).

The twelve-bar blues (or blues changes) is one of the most prominent chord progressions in popular music. The blues progression has a distinctive form in lyrics, phrase, chord structure, and duration. In its basic form, it is predominantly based on the I, IV, and V chords of a key. Mastery of the blues and rhythm changes are "critical elements for building a jazz repertoire".