Islam is an Arabic word and denotes submission,surrender and obedience. As a religion, Islam stands for complete submission and obedience to Allah - that is why it is called Islam. The other literal meaning of the word Islam, comes from the word 'salam' which means 'peace' and this signifies that one can achieve real peace of body and mind only through submission and obedience to Allah. Such a life of obedience brings peace of the heart and establishes real peace in society at large.
"Those who believe and whose hearts find rest in the remembrance of God-indeed it is in the remembrance of Allah alone that the act of righteously, joy is for them, and a blissful home to return to." (The Quran 13: 28-29)
This message was preached by all the Prophets of God, who guided man to the Right path. But man not only veered away from the right path again and again, but also lost or distorted the code of guidance which the Prophets had bequeathed. That is why the other Prophets or Messengers were sent to re-state the original message and guide man back to the right path. That means, all the Prophets are also preached the same message, the same cause, the same religion, and that is Islam. But it is not called by that name until God send to all human kind the last of all Prophets, Muhammad (peace be upon him) who presented God's guidance in its final form and arrangeed to preserve it for all time. It is this guidance which is now known as Islam and which is enshrined in the Quran's and the life-example (sunnah) of the Prophets. The basis Islamic concept is that the whole universe was created by God, whom Islam calls Allah (or Ilahi or Ila or Ya HuAllahu or Allahu or Rabb). The same name is also addressed by all Semitic Religions (Christianity and Judaism) in it's Hebrew term as Ila, Eli, Eloh, Alla or YahuaElohim which means God. Allah is the Lord and the Sovereign of the Universe. He is the Lord of the Universe which He Alone sustains. He created man and appointed for each human being a fixed period of life which he is to spend upon the earth. Allah has prescibed a certain code of life as the correct one for Him, but has at the same time conferred upon man some freedom of choice as to whether or not he adopts this code as the actual basis of his life. One who choses to follow the code revealed by God becomes a Muslim (those who surrender, or submitter or believer) and one who refuses to follow it becomes a kafir (disbeliever)