The orthography of Irish refers to the set of rules and grapheme-phoneme (sound-letter) correspondences used to write this Celtic language. Irish today is written in a modified Latin alphabet, but the earliest writings originating in Ireland, of Primitive Irish, are in the Ogam script, developed around the fourth to fifth centuries). From around the seventh century, Old Irish began to be written in an insular Latin script, which retained some Ogam features.[1]