It was composed by Charles Gounod in 1859 during the romantic era, based on the harmony and texture of J.S.Bach's Prelude No.1 in C Major from Well-Tempered Clavier Book I (BWV 846). It is a setting of the standard Latin Ave Maria text.
The piece is played calmato, perhaps at andante (walking pace). There are many different instrumentations of the Charles François Gounod version, the most popular are: violin and guitar (giving a more baroque feel), string quartet, piano solo and even trombones. Through all of these however, it maintains its familiar relaxing melody.