A jail is a correctional institution used to detain persons who are in the lawful custody of the government. A jail is distinguished from a prison in that jails are customarily for the detention of those either awaiting trial or serving sentences of less than one year. However, in common use, jail is often employed as a synonym for prison.
The word originally derived from the Latin word "cavea" (cage), and was originally spelt "gaiole", "jaiole, or "jaile" when first introduced into Middle English around 1200 A.D. 
Jail is mentioned several times in both the Old and New Testaments. Many inmates turn to the Bible for the strength needed to become rehabilitated.