He was born named Filippo in Nola, in Campania, the son of Giovanni Bruno, a soldier. He took the name Giordano on becoming a Dominican friar at the Monastery of Saint Domenico near Naples. In 1572 he was ordained a priest.
In 1576 he left Naples to avoid the attention of the Inquisition. He left Rome for the same reason and abandoned the Dominican order. He travelled to Geneva and briefly joined the Calvinists, before he was excommunicated and forced to leave for France.
He stayed in France for seven years, enjoying the protection of some powerful patrons. While in France he published twenty books, including several on memory training, Cena de le Ceneri (1584), and De l'Infinito, Universo e Mondi (1584). In Cena de le Ceneri he defended the theories of Copernicus, albeit rather poorly. In De l'Infinito, Universo e Mondi, he argued that the stars we see at night were just like our Sun, that the universe was infinite, with an infinite number of worlds, and that all were inhabited by intelligent beings (see the Drake equation).
In 1586, following a violent quarrel about "a scientific instrument", he left France for Germany, and in Helmstadt he was excommunicated by the Lutherans. In 1591 he accepted an invitation to Venice. There he was arrested by the Inquisition and tried before being extradited for trial in Rome in 1593.
In Rome he was kept imprisoned for six years before he was tried. His trial was overseen by the inquisitor, Cardinal Saint Robert Bellarmine. He refused to retract his views and was declared a heretic and handed over to secular authorities on January 8 1600 and burned at the stake on February 17 1600 in Campo de' Fiori, a popular Roman square.
It is claimed that he was burned for his Copernicanism, but this is uncertain, since his theological beliefs were also sufficiently unorthodox. The Catholic church claimed he was actually on trial for docetism. At his trial, he said: Perhaps you, my judges, pronounce this sentence against me with greater fear than I receive it. All his works were placed on the Index Librorum Prohibitorum in 1603.
Four hundred years after his execution, official expression of "profound sorrow" and acknowledgement of error at Bruno's condemnation to death was made, during the incumbency of John Paul II.