(Haqq al Yaqin). There are three stages of Certainty 'Ilm al Yaqin (The Knowledge of Certainty), 'Ayn al yaqin (The Eye of Certainty) and Haqq al Yaqin (The Truth of Certainty). When considering this triad the Truth of Certainty could be likened to being consumed by the flames of a blazing fire after the two preliminary stages of 'Ilm al Yaqin (merely hearing a description of that fire) and 'Ayn al Yaqin (actually seeing the light of the flames of a fire). Haqq al Yaqin is the final stage in the ascent before attaining Real Islam. The seven levels of knowledge through which the traveller (Salik) must pass are Islam; Iman; Ihsan; 'Ilm al Yaqin; 'Ayn al Yaqin; Haqq al Yaqin and Islam. (Surrender, Faith, Perfection, Knowledge of Certainty, The Eye of Certainty, The Truth of Certainty and Total Surrender and Submission).
Islam means peace and the person who follows this peace is called the Muslim. From another root meaning of the word, Islam means complete submission and surrender, and the person who submits and surrenders himself to the will of his Lord is the person who has accepted Allah as his Creator, Sustainer, Lord and the Master of the Day of Judgement.
So from both the definitions Islam means a way of life for people who have opted to follow peace as opposed to chaos, order as opposed to disorder, discipline as opposed to indiscipline, submission as opposed to refusal, surrender as opposed to insolence, obedience as opposed to disobedience etc. All these things combined together to define Islam as away of life by which a person becomes a follower of peace and not a follower of chaos. And the followers of peace are the Muslims whose duty it is: "to establish peace and what is good, and to prevent chaos and what is evil, and they are the best people." (Al-Qur'an 3:110)