The Persian alphabet, also known as the Perso-Arabic script, is the right-to-left alphabet used for the Persian language. It is a variation of the Arabic script with four additional letters: پ چ ژ گ, in addition to the obsolete ڤ that was used for the sound. This letter is no longer used in Persian, as the -sound changed to, e.g. archaic زڤان > زبان 'language'.