Melchizedek, whose name means my king is righteous, was the King of Salem and a priest of God.
Salem means peace. Jebusites named the city Jebus.The two names were later joined together to form Jerusalem, which means Habitation of peace.
Abraham presented Melchizedek with a tithe (a tenth) of all the booty he had gathered after a great battle. By this act Abraham indicated that he acknowledged God's hand in his victory over his enemies.
Melchizedek's existence shows that there were people other than Abraham and his family who served the true God.
18 Then Melchizedek king of Salem brought out bread and wine. He was priest of God Most High, 19 and he blessed Abram, saying,
"Blessed be Abram by God Most High,
Creator of heaven and earth.
20 And blessed be God Most High,
who delivered your enemies into your hand."
Then Abram gave him a tenth of everything.