Cuneiform is a logo-syllabic writing system that was used to write several languages of the ancient Near East. The script was in active use from the early Bronze Age until the beginning of the Common Era. Cuneiform scripts are marked by and named for the characteristic wedge-shaped impressions (Latin: cuneus) which form their signs. Cuneiform is the earliest known writing system and was originally developed to write the Sumerian language of southern Mesopotamia (modern Iraq).

Over the course of its history, cuneiform was adapted to write a number of languages in addition to Sumerian. Akkadian texts are attested from the 24th century BC onward and make up the bulk of the cuneiform record. Akkadian cuneiform was itself adapted to write the Hittite language in the early 2nd millennium BC. The other languages with significant cuneiform corpora are Eblaite, Elamite, Hurrian, Luwian, and Urartian. The Old Persian and Ugaritic alphabets feature cuneiform-style signs; however, they are unrelated to the cuneiform logo-syllabary proper. The latest known cuneiform tablet, an astronomical almanac from Uruk, dates to AD 79/80.

Cuneiform was rediscovered in modern times in the early 17th century with the publication of the trilingual Achaemenid royal inscriptions at Persepolis; these were first deciphered in the early 19th century. The modern study of cuneiform belongs to the ambiguously named field of Assyriology, as the earliest excavations of cuneiform libraries during the mid-19th century were in the area of ancient Assyria. An estimated half a million tablets are held in museums across the world, but comparatively few of these are published. The largest collections belong to the British Museum (approximately 130,000 tablets), the Vorderasiatisches Museum Berlin, the Louvre, the Istanbul Archaeology Museums, the National Museum of Iraq, the Yale Babylonian Collection (approximately 40,000 tablets), and the Penn Museum.

Writing began after pottery was invented, during the Neolithic when clay tokens were used to record specific amounts of livestock or commodities. These tokens were initially impressed on the surface of round clay envelopes (clay bullae) and then stored in them. The tokens were then progressively replaced by flat tablets, on which signs were recorded with a stylus. Writing is first recorded in Uruk, at the end of the 4th millennium BC, and soon after in various parts of the Near-East.

An ancient Mesopotamian poem gives the first known story of the invention of writing:

Because the messenger's mouth was heavy and he couldn't repeat [the message], the Lord of Kulaba patted some clay and put words on it, like a tablet. Until then, there had been no putting words on clay.

— Enmerkar and the Lord of Aratta, c. 1800 BC

The cuneiform writing system was in use for more than three millennia, through several stages of development, from the 31st century BC down to the second century AD. The latest firmly dateable tablet, from Uruk, dates to 79/80 AD. Ultimately, it was completely replaced by alphabetic writing, in the general sense, in the course of the Roman era, and there are no cuneiform systems in current use. It had to be deciphered as a completely unknown writing system in 19th-century Assyriology. It was successfully deciphered by 1857.