Laws or orders. There are six types in Islam:
1. Compulsory (Wajib)
2. Order without obligation (Mustahab)
3. Forbidden (Muharram)
4. Disliked but not forbidden (Makruh)
5. Legal and allowed (Halal)
6. no law defined/required (Mubah)

Most clerics and teachers will only state the first 5 of the laws. The sixth one is essential because it asserts the fact that some things are ambiguous and doesn't neccessarily.