contemporary Estonian composer, classified as a minimalist. 2011−2018 his music has been the most performed in the world by living classical composers, according to the bachtrack database.
1945-1953 he studied piano at a local music school under the guidance of Ille Martin, tried to compose his own compositions. 1950-1954 A. Piartas studied at the Rakvere Higher School. In 1954, he continued his studies at the Tallinn Conservatory (music school) under the guidance of Veljos Tormis. 1954-1956 A. Piartas performed military service, played the oboe, piano and percussion instruments in the soldiers' ensemble. 1957-1963 A. Piartas studied at the Tallinn Conservatory (music academy), studied composition under the guidance of Heino Eller. 1958-1967 worked as a sound engineer at Estonian Radio, 1961. became a member of the Union of Estonian Composers. in 1962 A. Piartas won the First Prize at the Forum of Young Composers in Moscow for the children's cantata "Our Garden" and the oratorio "Pasauli žingsniai". His early works were in the classical tradition, mostly for piano. A. Piartas studied and used serialist technique, musical collage in his work. in 1964 became particularly interested in the works of J.S. Bach, wrote compositions imitating the Baroque style. A. Piartas worked on film music. in 1968 he wrote the composition Credo, which ends the first period of A. Piart's work. Credo was banned in the USSR for more than a decade due to the religious meaning of the name.

1968-1976 period, A. Piartas was looking for a creative style of his music, studied the simplest two-part counterpoint, studied works of early European music and Gregorian chant. Searches were crowned in 1976. the composition Für Alina, in which the composer used a peculiar technique, which he called the term tintinnabuli. The basis of this technique was a homophonic motif of two parts moving at most only one step around the root note (not necessarily the tonic). 1976-77 the composer worked intensively on this technique, creating 15 works, among which the most famous were Tabula Rasa, Fratres and "Song in Memory of Benjamin Britten". The religiosity and oversimplified composition of these works did not meet the approval of either the political functionaries of the then communist USSR or the representatives of academic music. The composer deeply professed the Russian Orthodox faith, to which he converted in 1972. married to second wife Nora. in 1980 A. Piartas emigrated from the USSR with his wife Nora and two young sons, settled in Vienna, and found connections with Universal Edition music publisher. A year later, he moved to Berlin. in 1982 created about 70 minutes long "St. John's suffering" became an exemplary work of A. Piarts tintinnabuli technique. in 1984 the composer began to cooperate with the "ECM Records" publishing company, authorizing the first recordings of his main compositions. Most of the composer's works of this period were short compositions for choir or vocal ensemble. The composer wrote them in various languages: German, Church Slavonic, Italian, English, Spanish.

in 1989 A. Piartas was awarded the Edison Classical Music Prize and nominated for the Grammy Award in the category of best contemporary composition for Passio. in 1990 A. Piart was awarded an honorary doctorate degree by the Tallinn Academy of Music. in 1991 his composition Miserere was nominated for a Grammy Award in the category of best contemporary composition, and the composer became an honorary member of the Royal Swedish Academy of Music in Stockholm. in 1992 A. Piartas returned from emigration to Estonia, kept his house in Berlin. in 2010 A. Piartas established a center of his name to archive and promote his work in Estonia. One of A. Piart's most famous works is Spiegel im Spiegel (1978), which was used in 2013. in the trailer of the famous movie "Gravity". His music was featured in the US Academy Award-winning films Fahrenheit 9/11 (2004) and There Will Be Blood (2007), Piart has been cited as an influence by Björk, Keith Jarrett, Radiohead and Lupe Fiasco. in 2011 A. Piartas dedicated the work Vater Unser to the 60th anniversary of the ordination of Pope Benedict XVI to the clergy, which was performed in the presence of the Pope.