Burnt offering : Hebrew olah; i.e., "ascending," the whole being consumed by fire, and regarded as ascending to God while being consumed. Part of every offering was burnt in the sacred fire, but this was wholly burnt, a "whole burnt offering." It was the most frequent form of sacrifice, and apparently the only one mentioned in the book of Genesis. Such were the sacrifices offered by Abel (Genesis 4:3,4, here called minhah; i.e., "a gift"), Noah (Genesis 8:20), Abraham (Genesis 22:2,7,8,13), and by the Hebrews in Egypt (Exodus 10:25).
The law of Moses afterwards prescribed the occasions and the manner in which burnt sacrifices were to be offered. There were "the continual burnt offering" (Exodus 29:38-42; Leviticus 6:9-13), "the burnt offering of every sabbath," which was double the daily one (Numbers 28:9,10), "the burnt offering of every month" (Numbers 28:11-15), the offerings at the Passover (Numbers 19-23), at Pentecost (Leviticus 23:16), the feast of Trumpets (Leviticus 23:23-25), and on the day of Atonement (Leviticus 16).
Free-will burnt offerings were also permitted (Leviticus 1:13), and were offered at the accession of Solomon to the throne (1 Chronicles 29:21), and at the reformation brought about by Hezekiah (2 Chronicles 29:31-35).