What is iman in islam?

In Islam, Iman means belief in Allah as the one and only God and in Prophet Muhammad as His final messenger, as well as in the holy books revealed to them, and in the Day of Judgment. It is one of the Five Pillars of Islam and is an essential part of a Muslim's faith. The belief in Iman is not only a matter of intellectual conviction, but it involves a total submission to Allah's will and living one's life according to the principles of Islam. In Arabic, the word 'iman' is derived from the root word 'amana' which means 'to be safe and secure.'