Gregorio Allegri was an Italian composer and priest born in 1582 in Rome. He is best known for his choral work, the Miserere, which is a setting of Psalm 51. This piece became famous for its beautiful harmonies and was traditionally performed during Holy Week in the Sistine Chapel. Allegri's music is characterized by its use of polyphony, where multiple independent melodies are sung simultaneously. The Miserere gained widespread acclaim, especially after Wolfgang Amadeus Mozart famously transcribed it from memory at the age of 14. Allegri passed away in 1652, leaving a lasting impact on sacred music.