Quipu were knotted cords made of different colored strings, with the knots and their positions representing numbers, quantities, and possibly other information. While the exact meaning of many quipus remains a mystery, they were used for:
* Census and tax records
* Accounting and financial transactions
* Calendar and astronomical observations
* Messages and communication
However, quipu was not a true written language:
* It lacked a phonetic representation of sounds. The knots only represented numbers and quantities, not words or concepts.
* It relied heavily on the memory and knowledge of the quipucamayoc (quipu keepers). The meaning of the knots could only be deciphered by those who had been trained to understand them.
So, while the Incas had an intricate system of record-keeping, it was not a written language. They communicated primarily through spoken language.