Spanish guitar and flamenco: compas, rasgueado and what the palos actually are
How flamenco guitar works: the twelve beat compas of solea and buleria, rasgueado and picado technique, the Phrygian cadence, and how it differs from classical Spanish guitar.
Flamenco is organised into palos, forms with their own rhythmic cycle and mood. Many of the central ones run on a twelve beat compas with accents in an uneven pattern rather than a regular four. The guitar's characteristic sound comes from rasgueado strumming, percussive golpe taps and the Phrygian cadence.
Palos, not songs
Flamenco is not a repertoire of tunes. It is a set of forms called palos, each with its own rhythmic cycle, harmonic tendency and emotional register. Solea is grave and slow. Buleria is fast and playful and shares the same twelve beat cycle. Alegrias is bright and major inflected. Tangos flamencos, which are nothing to do with Argentine tango, run in a straightforward four. Fandangos sit apart again.
A guitarist does not learn a flamenco piece so much as learn a palo and then play within it.
The twelve beat compas
The single hardest thing for an outside listener is that solea, buleria and alegrias run on a cycle of twelve beats with accents distributed unevenly, commonly on 12, 3, 6, 8 and 10. Counting from one and expecting a regular four will not work. The accents are the structure, and everything in the performance, including the dancer's footwork and the singer's entry, is placed against them.
This is a close cousin of the situation in Afro-Cuban music, where a twelve pulse cycle can be heard two ways at once. Different tradition, same demand on the ear.
What the right hand is doing
Rasgueado is the rolling strum produced by flicking the fingers outward in sequence, giving a continuous rhythmic surface rather than a single chord attack. Picado is fast single note running played with alternating index and middle fingers, rest stroke, for the melodic passages. Golpe is a percussive tap on the guitar's soundboard, which is why flamenco guitars carry a protective plate. Alzapua is a thumb technique combining single notes and brushed chords.
None of this is classical technique. A classical guitarist and a flamenco guitarist hold the instrument differently, sit differently and produce a different tone on purpose: flamenco favours attack and percussive edge over sustain and roundness.
The Andalusian cadence
The harmonic signature of flamenco is the descending progression that ends on the major chord built on the flattened second degree resolving to the tonic, most often heard in the Phrygian mode. It is the sound that makes a passage read as Spanish within two bars, and it is used constantly in film and in Latin music that wants an Andalusian colour, including bolero moruno.
Flamenco and Latin American music
Flamenco is Andalusian, not Latin American, and it is worth keeping the distinction. Its influence travelled to the Americas with Spanish colonisation and shows up in the guitar traditions of the Caribbean and Latin America, including the bolero. It is not, however, part of the Afro-Cuban rhythmic family the rest of this site covers, and its twelve beat cycles work on a different principle.
The Spanish Guitar Flamenco playlist page covers when to put this on rather than what it is.