Cuneiform writing has been used for more than three millennia in a vast area from the Mediterranean Sea to Iran, and from the Black Sea to Egypt(El Amarna). There, different cuneiform writing systems have been used by various populations speaking different languages. Cuneiform signs were imprinted on clay, on wood or ivory tablets covered with wax, or engraved on stone and metal. But the great majority of the recovered texts were written on unfired clay tablets. Up to now, ancient Near Eastern archaeologists have unearthed more than a million of original cuneiform texts which are deciphered and studied since the middle of the nineteenth century by Assyriologists. Traditionally, these scholars use to call themselves epigraphists, but when mentioning their source material, they usually speak about manuscripts. In order to understand this paradox, this contribution analyses the various characteristics of clay as a writing medium.