Tajweed refers to rules for reciting the Quran correctly. It involves beautifying the pronunciation. Angel Jibreel taught Prophet Muhammad Tajweed when revealing the Quran. Tajweed defines five articulation points for letters from the lips, nasal area, throat, tongue, and empty space of the mouth. It also describes rules for lengthening vowels, including causes and types of lengthening such as short, long, disconnected, connected, and natural lengthening.