The source of Jewish religious law is called the Torah (literally, teaching or law). There are two parts to the Torah: the written Torah and the Oral Torah. The written Torah, which was given by God to Moses in the 13th century BCE to Israel, is recorded in five books (Genesis, Exodus, Leviticus, Numbers, Deuteronomy). These books are also called the Pentateuch (which means five books) by Christians. The other sections of the Jewish Bible (also known as the Old Testament), the Prophets and Scriptures, also contain important teachings, but they don’t have the same authority as the Torah.
The Oral Torah is the expansion of the Divine law given in the written Torah through ancient tradition, textual interpretation and supplementary legislation (this legislation does not have the same force as the laws in the Torah). The teachings and instructions of the Oral Torah were written down in the 2nd century BCE to prevent it from forgotten. These collected writings are called the Mishna (derived from the Hebrew word for ‘teaching’ or ‘memorizing’).
In the centuries to come, Jewish religious authorities interpreted and expanded on the Mishna. Eventually these discussions and teachings were also collected in a series of volumes known as the Talmud (derived from the Hebrew word ‘to learn’). Together, the Mishna and the Talmud serve as the authoritative corpus of Jewish Oral Torah. Jewish religious authorities continue to expand, adapt and refine its teachings and laws to this day