Goliath (/ɡəˈlaɪəθ/) (Hebrew: גָּלְיָת, Modern Golyat, Tiberian Golyāṯ; Arabic: جالوت, Ǧālūt (Qur'anic term), جليات Ǧulyāt (Christian term)) or Goliath of Gath (one of five city states of the Philistines) was a giant Philistine warrior defeated by the young David, the future king of Israel, in the Bible's Books of Samuel (1 Samuel 17).
The original purpose of the story was to show David's identity as the true king of Israel. Post-Classical Jewish traditions stressed Goliath's status as the representative of paganism, in contrast to David, the champion of the God of Israel. Christian tradition gave him a distinctively Christian perspective, seeing in David's battle with Goliath the victory of God's king over the enemies of God's helpless people as a prefiguring of Jesus' victory over sin on the cross and the Church's victory over Satan.
The phrase "David and Goliath" has taken on a more secular meaning, denoting an underdog situation, a contest where a smaller, weaker opponent faces a much bigger, stronger adversary.(Wikipedia)