"Torah", in the strict sense, refers to the Pentateuch (the first five books of the Old Testament). It appears to have been put together from 4 sources:
- the "P" source (for "Priestly Author") - appears to have been written just after the Babylonian exile in the 500s BC. This material includes the first chapter of Genesis and nearly all of Leviticus.
- the "J" source (from the German equivalent for "Yahwist") - most likely lived in the southern kingdom of Judah sometime between the 900s and 700s BC. This material includes Genesis 2 through 11.
- the "E" source (for "Elohist") - probably wrote a few generations after J, in the northern kingdom of Israel. This material begins in Genesis 12 with the story of Abraham.
- the "D" source (for "Deuteronomist") - wrote in about the 600s BC. He (or they) wrote large parts of Deuteronomy, and also shaped the books of Joshua, Judges, Ruth, Samuel, and Kings from various documents.
"R" (the compiler or "Redactor") gathered the four strands and edited them together, probably sometime in the late 400s BC.
Torah, in the larger sense, can refer to the Hebrew scriptures in general (including Isaiah, which was compiled from 3 different sources, written at different times and places).
Brush Up Your Bible! (1993), by Michael Macrone (part of a series of such books from Random House)