Cain is a Biblical figure in the Book of Genesis within Abrahamic religions. He is the elder brother of Abel and the firstborn son of Adam and Eve, the first couple in the Bible. He was a farmer who gave an offering of his crops to God. However, God was not pleased and favored Abel's offering over Cain's. Out of jealousy, Cain killed his brother, for which he was punished by God with the curse and mark of Cain.

Source: Wikipedia