punch cards

Punch cards are an early form of data storage and input for computers, consisting of pieces of stiff cardboard with a grid of holes. Information is encoded by punching holes in specific positions on the card, which a machine reads as digital signals. Used from the late 19th to mid-20th century, punch cards enabled automation of data processing tasks like census counting and business data management. They required physical handling and were an important step in developing modern computing, serving as both input and output medium before digital storage methods became prevalent.