Question
When does the soul enter the body? Where is it until then?
Answer
According to the Talmud (Yevamos 62a), unborn souls are “stored” in a place called GUF (not to be confused with the usual translation of “GUF” as “body”). The souls study Torah, but they forget it when they are born. (If this applies to non-Jewish children, they must study the Noahide Laws.) The soul enters the body at conception (Talmud Sanhedrin 91b).