Letters that extend a vowel
Madd (مَدّ) means extension or lengthening. Huroof-e-Madd are the letters that carry a long vowel when their required preceding vowel is present. They are Alif ا, Waaw Sakinah وْ, and Yaa Sakinah يْ.
A short Harakah lasts briefly. A basic Madd sound continues for two vowel counts. The consonant before the Madd letter begins the syllable; the Madd letter extends its vowel smoothly without a break.
The Madd letter itself normally carries no vowel sign. Its identity depends on both the letter and the Harakah immediately before it.