Which type of writing did the harappans use?

Answer 1

Well over 400 distinct Indus symbols have been found on seals or ceramic pots and over a dozen other materials, including a "signboard" that apparently once hung over the gate of the inner citadel of the Indus city of Dholavira. Typical Indus inscriptions are no more than four or five characters in length, most of which (aside from the Dholavira "signboard") are exquisitely tiny; the longest on a single surface, which is less than 1 inch (2.54 cm) square, is 17 signs long; the longest on any object (found on three different faces of a mass-produced object) has a length of 26 symbols.

While the Indus Valley Civilization is often characterized as a "literate society" on the evidence of these inscriptions, this description has been challenged on linguistic and archaeological grounds: it has been pointed out that the brevity of the inscriptions is unparalleled in any known premodern literate society. Based partly on this evidence, a controversial paper by Farmer, Sproat, and Witzel (2004), [4] argues that the Indus system did not encode language, but was instead similar to a variety of non-linguistic sign systems used extensively in the Near East and other societies. It has also been claimed on occasion that the symbols were exclusively used for economic transactions, but this claim leaves unexplained the appearance of Indus symbols on many ritual objects, many of which were mass produced in molds. No parallels to these mass-produced inscriptions are known in any other early ancient civilizations.