Diversity of suffix ‘-i’, called ‘ya’, in Persian language, which is of important consideration, for any reason, has not been able to attract scholars and grammarians in the field of Persian language. Here is an attempt to mention different kinds of ‘ya’ and to explain their applications, relying on grammar books, dictionaries, and today native application. The character generally has three types of applications in Persian language. It is firstly one of the Persian alphabet, so it primarily functions as a ‘phoneme’. It is applied in its second function when appears in the form of ’morpheme’, such as ‘-i’ in ‘mardi rad shod’ (a man passed) with usage of indefinite article. The third function appears when it comes in the place of a word, because it is one of the six types of pronouns. So, ‘ya’ is applied in three forms: phoneme, morpheme and word. In continue, it is attempted to explain these kinds in more details.