The Old Testament is the first division of the Christian biblical canon, which is based primarily upon the Hebrew Bible or Tanakh, a collection of ancient religious Hebrew writings by the Israelites. The second division of Christian Bibles is the New Testament.

The Old Testament is the first and longer part of the Christian Bible, based primarily on the 24 books of the Hebrew Bible (Tanakh). It is a collection of ancient religious, historical, poetic, and prophetic texts written in Hebrew and Aramaic that details the covenant between God and the Israelites, covering creation, law, and history.
Key Aspects of the Old Testament:
Structure: Divided into three main sections: the Torah (Law/Pentateuch), Nevi’im (Prophets), and Ketuvim (Writings).
Content: Contains accounts of creation, the patriarchs (Abraham, Isaac, Jacob), the Exodus from Egypt, the establishment of the Israelite kingdom, and messages from prophets warning of judgment and offering hope.
Purpose: In Judaism, it is the foundational sacred text. In Christianity, it is viewed as the history of salvation leading up to the birth of Jesus Christ, containing prophecies fulfilled in the New Testament.
Canon Differences: While Protestant traditions typically recognize 39 books, Catholic and Orthodox traditions include additional texts known as the Deuterocanonical books or Apocrypha.
History: The texts were written over centuries, concluding with the history of the Jewish people’s return from exile and the rebuilding of Jerusalem.
It is often called the “Old Covenant” in contrast to the New Testament’s “New Covenant” of grace.

The Bible was written by approximately 40 different men from diverse backgrounds—including prophets, kings, fishermen, and scholars—over a span of roughly 1,500 years. While many books are anonymous, traditional authorship attributes the texts to individuals such as Moses, David, Solomon, Isaiah, Jeremiah, Matthew, Mark, Luke, and Paul.

Key Authors of the Bible

Old Testament (Traditional Attribution): Moses (Genesis–Deuteronomy, Job), Joshua, Samuel, Gad, Nathan, Ezra, Nehemiah, Mordecai, David, Solomon, Asaph, Heman, Ethan, and the prophets (Isaiah, Jeremiah, Ezekiel, Daniel, and the 12 minor prophets).

New Testament (Traditional Attribution): Matthew, Mark, Luke (also wrote Acts), John, Paul (13 letters), James, Peter, and Jude.

Key Details Regarding Authorship

Time Span: The writings took place over 1,500 years, with diverse perspectives contributing to a cohesive message.
Anonymity: Many books do not explicitly state their author, leading to reliance on traditional, historical, or scholarly assumptions (e.g., Mordecai for Esther, Ezra/Nehemiah for Chronicles).
The Four Evangelists: Matthew, Mark, Luke, and John are credited with the Gospels, with Luke being the only non-Jewish writer.

The books of the Old Testament were written over roughly a thousand years, with composition starting around 1400-1200 BCE (Pentateuch/Torah) and concluding around 400 BCE (like Malachi, Ezra, Nehemiah), though specific dates vary by book and scholar, with much material passed down orally before being written. These texts, primarily in Hebrew, cover the relationship between God and Israel, developing gradually through various authors and historical moments.
Key Periods & Books
Early Writings (c. 1400–1000 BCE): The first five books (Genesis, Exodus, Leviticus, Numbers, Deuteronomy), often called the Torah or Pentateuch, are traditionally linked to Moses and the period following the Exodus.
Prophetic & Historical Books (c. 900–500 BCE): This era saw the rise of written historical accounts (like Joshua, Judges, Samuel, Kings) and the words of the prophets (Isaiah, Jeremiah, Ezekiel, etc.), often compiled after significant events like the Babylonian Exile.
Later Books (c. 500–400 BCE): The final books, such as Ezra, Nehemiah, and Malachi, were completed after the return from exile, solidifying the collection.
Process
Oral Tradition: Stories and laws were memorized and passed down for generations before being written.
Gradual Compilation: The entire collection wasn’t written at once but developed across centuries by numerous authors, from well-known figures like David to lesser-known scribes.
Language: Mostly Hebrew, with small portions in Aramaic.