The Indus script has not been deciphered so far, but overlaps of letters on some of the potsherds from Kalibangan show that writing was 'boustrophedon' or from right to left and from left to right in alternate lines.
We are not certain about the writing media, but a small pot found at Chanhu-daro is regarded as an inkwell.
The Harappan script is perhaps logographic: there are 375 to 400 signs, which rules out an alphabet (where one sign stands for one vowel or consonant) because alphabets usually have not more than thirty-six signs.
It is not yet clear whether these signs are ideographic, logographic or of some other type. The Harappan language was probably agglutinative, or a language which added suffixes to an unchanging root, a characteristic of the Dravidian language family.
This has not led several scholars to conclude that the Harappan language is not of the Indo-European family, nor is it close to Sumerian, Hurrian, or Elamite.
It is related to any modern language family; it appears to be the Dravidian, presently spoken throughout South India. Father H. Heras has claimed that the Harappan language was a very primitive form of Tamil.