Arabic alphabet - Wikipedia
https://en.wikipedia.org/wiki/Arabic_alphabetThe basic Arabic alphabet contains 28 letters. Adaptations of the Arabic script for other languages added and removed some letters, as for Persian, Ottoman Turkish, Central Kurdish, Urdu, Sindhi, Malay, Pashto, Arwi and Arabi Malayalam, all of which have additional letters as shown below. There are no distinct upper and lower case letter forms.