The prophets were people who, under the inspiration of the Holy Spirit, prophesied, that is, foretold what would be in the future, especially about the coming Saviour of the world. They announced the will of God, taught the people true faith and piety, and performed various signs and miracles.
They exposed the idolatry of the Hebrews and called them to repent. Some of them preached only orally, and others, in addition, left behind sacred books, written by them under the inspiration of the Holy Spirit.
The most famous of the prophets living in the Israelite kingdom were, Elijah, Elisha and Jonah, and of the prophets living in the Judean kingdom, Isaiah, Jeremiah, Micah, Ezekiel and Daniel.
(from: The Law of God by Fr. Seraphim Slobodskoy)