The ancient form of writing used in Mesopotamia is called cuneiform. Developed by the Sumerians around 3200 BCE, cuneiform writing involved pressing a reed stylus into soft clay tablets to create wedge-shaped characters. This system was used for recording various types of information, including administrative records, legal codes, literature, and scientific knowledge. Cuneiform is one of the earliest writing systems in human history and played a crucial role in the administration, commerce, and cultural expression of ancient Mesopotamian societies, influencing subsequent writing systems.