Orthography
Languages that are written in the Latin alphabet may indicate nasal vowels by a trailing silent n or m, as is the case in French, Portuguese, Bamana, or Yoruba. In other cases they are indicated through diacritics: Portuguese also marks nasality with a tilde, ã, õ, before other vowels; Polish, Navajo, and Elfdalian use a hook underneath the letter, called an ogonek, as in ą, ę. Other languages may use a superscript n: aⁿ, eⁿ. In the International Phonetic Alphabet, nasal vowels are denoted by a tilde over the symbol for the vowel, as in Portuguese.
Abugida scripts, which are used for most Indian languages, use the chandrabindu (◌̐) diacritic and its variations to denote nasal vowels and nasal junctions between consonants.
The Nasta'liq script used by Urdu denotes nasalization by employing the Arabic letter ˂ن˃ nūn but removing the dot (˂ں˃), called nūn ghunna. Nasalized vowels occur in classical Arabic, but not in contemporary speech or standard Arabic. There is no orthographic way to denote the nasalization, but it is systematically taught as part of the essential rules of tajweed employed while reading the Qur'an. Nasalization usually occurs in recitation when a final ˂ن˃ nūn is followed by a ˂ي˃ yāʼ.
Read more about this topic: Nasal Vowel