Punchcard

A punchcard is a piece of stiff paper with punched holes used to store and process data in early computing and data-processing systems. Each card holds data in its columns; the presence or absence of holes in specific rows encodes characters, digits, or control information. Historically, punched cards were first used to tabulate data by Herman Hollerith for the 1890 US Census, leading to the development of card-processing machinery. IBM popularized the 80-column punched card and mechanical card punches and readers, which became the cornerstone of business data processing from the mid-20th century.

In operation, a deck of cards served as a program plus data: a stack of punched cards created by card punches; a computer would read the deck in sequence, perform operations, and print results. Card decks also served as storage media; although limited in capacity, they were portable and could be sorted, merged, and filtered with card sorters and collators. Programming was commonly done by writing source programs on cards, with multiple decks for source, listings, and executable jobs; languages such as Fortran and COBOL were compiled from card decks.

With advances in magnetic tape, disk, and high-level programming languages, punched cards gradually declined after the 1970s, but remained in use in some environments into the 1980s and 1990s. The term sometimes also refers to the standard 80-column IBM card, which became a convention in many data-processing systems, and to the broader culture of deck-based programming.