Chacham Yosef Chaim was born in 1832 in the city of Baghdad where his father was the Rabbi. (Chacham [wise man] is commonly used among Sephardim as equivalent to Rabbi.) When his father passed away, Rabbi Yosef Chaim was only twenty five years old. Nevertheless, the Jews of Baghdad accepted him to fill his father's place and Rabbi Yosef Chaim became the Rabbi of Baghdad.
Chacham Yosef Chaim was a great leader who guided his people through a time of religious upheaval. His contribution to Jewry was not restricted to Baghdad. His opinion on halachic (Jewish law) issues was sought throughout the Sephardi world and is still followed by thousands of people from these communities. Indeed, his decisions are considered to be of halachic significance even outside of the Sephardi communities.
Chacham Yosef Chaim authored many works, both of halakhah and agadah (sections of the Talmud that deals with esoteric, non-legal subjects). His most famous book is Ben Ish Chai, a book based upon the weekly portion of the Torah with a discussion of the portion and practical halakhah. This book is considered the standard reference in all religious Sephardi homes and is studied by Jews worldwide. Due to the popularity of this book, Rav Yosef Chaim came to be known by its name and today he is referred to universally as the Ben Ish Chai.
Sources: Great Jewish Leaders