ISLAM is derived from the Arabic root "SALEMA": peace, purity, submission and obedience. In the religious sense, Islam means submission to the will of God and obedience to His law.
Everything and every phenomenon in the world, other than man is administered TOTALLY by God-made laws i.e. they are obedient to God and submissive to His laws i.e. they are in the STATE OF ISLAM. Man possesses the quality of intelligence and choice, thus he is invited to submit to the good will of God and obey His law ie. become a Muslim. Submission to the good will of God, together with obedience to His beneficial law, i.e. becoming a Muslim is the best safeguard for man's peace and harmony.
Islam dates back to the edge of Adam and its message has been conveyed to man by God's Prophets and Messengers including Abrahim, Moses, Jesus and Muhammad. Islam's message has been restored and enforced in the last stage of the religious evolution by God's last Prophet and Messenger Muhammad.
The word Allah in the Arabic language means God, or more accurately The One and Only Eternal God, Creator of the Universe, Lord of all lords, King of all kings, Most Compassionate, Most Merciful. The word Allah to mean God is also used by Arabic speaking Jews and Christians.