Alif al-maddألف مَدِّيَّة
Preceded by فتحة (fatḥa)A sukūn-carrying alif preceded by a fatḥa. Elongates the 'a' sound for 2 counts.
Three letters — ا, و, and ي — can act as elongation letters when they carry a sukūn and are preceded by a matching short vowel. Their sound is held for 2 counts in normal recitation (longer in specific tajwīd contexts).
A sukūn-carrying alif preceded by a fatḥa. Elongates the 'a' sound for 2 counts.
A sukūn-carrying wāw preceded by a ḍamma. Elongates the 'u' sound for 2 counts.
A sukūn-carrying yā' preceded by a kasra. Elongates the 'i' sound for 2 counts.
Quranic recitation distinguishes several advanced types of madd (madd muttaṣil, munfaṣil, ʿāriḍ li-s-sukūn, lāzim, badal) that may be held for 4 or 6 counts. Those rules are covered under tajwīd — outside the scope of this reference page. For now, any madd letter you encounter can be safely held for 2 counts.