The Lawful and Unlawful
As a fundamental principle, everything is permitted in Islam except those things that have been expressly forbidden by Allah. In Islam, forbidden things are known as haram, and permitted things are known as halal.
Muslims rely on scriptural text, reasoning, and the conclusions of scholars when deciding on the legality of a particular matter. In the end, there is no individual or governing body that has the sole duty or right to interpret Islamic law. Muslims are left to follow the clear guidance as they best understand it.
Muhammad advised his followers to steer clear of doubtful things and stick to what they know for sure. He said: “The lawful is clear, and the unlawful is clear, and between them are things which are doubtful and not known to most of you. So anyone who keeps away from the doubtful things, in fact he is protecting his faith and honor, and he who indulges in doubtful acts falls into fault.”
The word haram means prohibited, forbidden, or unlawful. The word halal means allowed, permitted, or lawful. Muslims also recognize a gray area, makrooh, which describes that which is not forbidden but is disliked, undesirable, or doubtful — thus, best avoided.
The Qur'an warns people against making lawful things forbidden, and vice versa, based on their own opinions. “And do not say concerning the falsehood which your tongues utter, ‘This is halal and that is haram,’ in order to fabricate a lie against Allah. Assuredly, those who fabricate a lie against Allah will not prosper” (Qur'an 16:116). Muslims are always very careful when determining or instructing others about the lawfulness or unlawfulness of a course of action, for fear of leading other people astray and falling into this category of people who “lie” about God's legislation.