Rabbi Joseph ben Ephraim Caro made Jewish law (halacha) available to the masses. His major works, the Beit Yosef and the Shulhan Arukh, are considered by many to be the ultimate authorities in halacha.
Much of Caro's early life is uncertain. He was born in 1488 in either Spain or Portugal. If his birthplace was Spain, his family probably left for Portugal after the Spanish expulsion in 1492. After the expulsion from Portugal in 1497, Caro traveled with his family to Turkey. Throughout the 30 years he lived there, Caro settled in many areas of Turkey, so the place of his arrival is unclear. Caro first studied under his father, Ephraim, a renowned Talmudist. Ephraim died when Joseph was still young, however, and Joseph was brought up by his uncle, Isaac Caro.
Between 1520 and 1522, Caro met the mystic, Solomon Molcho, who's martyrdom — he was burnt at the stake in 1532 — made Caro want to die of a similar fate. Caro was also influenced in Turkey by Kabbalists Joseph Taitazak and Solomon Alkabez.
In 1536, Caro left Turkey and spent time in Egypt before continuing on to Safed, Palestine. There, he met Jacob Berab who, as part of his plan to reinstitute ordination of judges, rabbis and elders, a practice that had been abandoned for generations, ordained Caro in 1538. Caro later tried to ordain his own student, Moses Alshech, but in the end gave up due to opposition and wrote in one work that "nowadays we have no ordained dayanim (judges)."
After Berab left Safed in 1538, Caro was seen as the leader of the Safed scholars. He served as head of the communal council of Safed, and led a yeshiva of approximately 200 students. He wrote hundreds of responsa to halachic questions from all over the Diaspora. He also got involved in non-halachic issues. For example, when French Jews were treated unjustly with regard to taxes, they wrote to Caro, who's subsequent letter restored them their rights.
Caro's main focus was his halachic works. He began the Beit Yosef, a commentary on Jacob ben Asher's Arba'ah Turim, in 1522, when he was 34 years old, and finished it 20 years later. He consulted 32 Talmudic and rabbinical sources and discussed every law, starting with its source in Talmud, tracing its development, discussing every divergent view and finally ruling on the law. His rulings were generally based on the majority view of Isaac Alfasi, Maimonides and Asher ben Jehiel, though he did retain some discretion to insert his own views, particularly when there was no clear decision. The Beit Yosef was published in 1555.
The Shulhan Arukh, a concise version of the Beit Yosef that cites only the final ruling on laws, has become known as Caro's most important work. Although he wrote it chiefly for "young students," it became known as the authoritative halachic work for all Jews. There was much criticism of the Shulhan Arukh as a sole halachic authority, and commentaries, such as the Bayit Hadash of Joel Sarkes, sprung up in opposition. Also, the Shulhan Arukh was written mostly according to Sephardic tradition, so Moshe Isserles supplemented it with a commentary dictating Ashkenazic traditions where applicable. Other commentaries, such as Alexander Falk Hakohen and a variety of mid-17th century writers, established the credibility and authority of Caro's work.
Another one of Caro's major halachic works is the Kesef Mishna, a commentary on Maimonides' Mishneh Torah. Other halachic books include Kelalei ha_Talmud and Bedek ha_Bayit. He also wrote many responsa to questions on the Shulhan Arukh.
Caro was also a Kabbalist. He believed that a heavenly mentor, called a "maggid" visited him regularly. Caro recorded the messages that the maggid told him and parts of his notebook are printed in the book Maggid Mesharim.