Satan is the grand adversary of God and men (1 Peter5:8). The personal identification of Satan with the devil is asserted in Revelation 12:9; 20:2.
Read more:
His Origin and Mission (Part 1)
http://www/apologeticspress.org/articles/109
His Origin and Mission (Part 2)
http://www/apologeticspress.org/articles/112
Is Satan “Lucifer”?