Foto of cuatro "antiguo" Courtesy of the Puerto Rican Cuatro Project
As the Spanish colonized the islands of the Caribbean they brought many things, including musical instruments. Guitars were very popular and as time passed several new variants developed. At least four different instruments were adapted from the six-string Spanish classical guitar: the requinto, the bordonua, the cuatro, and the triple, each of which produces a unique tone and pitch.

Unique to Puerto Rico, and the one for which greatest number of adaptations and compositions have been written, is the cuatro, a guitar-like instrument. Originally the cuatro had only four strings and was similar to the vihuela. However around 1875, it was changed to five sets of double strings. The name 'cuatro' (translated as 'four') comes from the early, 4 string version which is known as the 'cuatro antiguo'. It happens that the tuning of the modern cuatro is in variables of half-octaves (that is, fourths). Thus, it is tuned from low to high B E A D G, with the B and E in octaves.

Usually carved from solid blocks of laurel wood and known for resonances and pitches different from those produced by its Spanish counterpart, this instruments graceful baroque body has been revered for decades as the national instrument of Puerto Rico. It is matte finished for protection without sacrificing tone to a heavy varnish. The instrument is sort of violin-shaped, more rounded like a guitar but with points at the inner bouts like a violin. The bridge is a classic guitar type, but the instrument is steel strung.

It is played with a flatpick and sounds like a cross between a 12-string guitar and a mandolin. In this example, the cuatro is used to play an instrumental version of the lovely ballad Obsesión composed by Pedro Flores.

The cuatro was the instrument of the jibaro, rural farmers, and also the name of the music they played on cuatros and guitars and güiros. It also was used to sing aguinaldos, the Puerto Rican Christmas songs, from house to house.

As William Cumpiano, of the Puerto Rican Cuatro Project, so aptly put it, "The cuatro holds a central place in Puerto Rico's cultural iconography, like the bagpipe for the Scot or the harp for the Irish. For many Puerto Ricans, the cuatro represents Puerto Rico. It has inspired its secular and religious festivities, and has provided a anchor for its cultural identity."