A stylus (plural: styli or styluses) is a writing utensil. The word is also used for a computer accessory (PDAs). It usually refers to a narrow elongated staff, similar to a modern ballpoint pen. Many styluses are heavily curved to be held more easily. Another widely-used writing tool is the stylus used by blind users in conjunction with the slate for punching out the dots in Braille.

Styli were first used by the ancient Mesopotamians in order to write in cuneiform, Egyptians (Middle Kingdom), and the Minoans of Crete (Linear A and Cretan Hieroglyphic) made in various materials: reeds that grew on the sides of the Tigris and Euphrates rivers and in marshes and down to Egypt where the Egyptians used styluses from sliced reeds with sharp points; bone and metal styli were also used. Cuneiform was entirely based on the "wedge-shaped" mark that the end of a cut reed made when pushed into a clay tablet, hence the name "cuneiform" from Latin cuneus = "wedge". The linear writings of Crete in the first half of the second millennium BC were made on sun dried clay tablets that were left to dry in order to become 'leather' hard before they were incised by the stylus. The linear nature of the writing was also dictated by the use of the stylus.