From Wikipedia:
Giovanni Pierluigi da Palestrina (c. 1525 – 2 February 1594) was an Italian Renaissance composer of sacred music and the best-known 16th-century representative of the Roman School of musical composition. He had a lasting influence on the development of church music, and his work has often been seen as the culmination of Renaissance polyphony.
In music, polyphony is one type of musical texture, where a texture is, generally speaking, the way that melodic, rhythmic, and harmonic aspects of a musical composition are combined to shape the overall sound and quality of the work. In particular, polyphony consists of two or more simultaneous lines of independent melody, as opposed to a musical texture with just one voice, monophony, or a texture with one dominant melodic voice accompanied by chords, which is called homophony.