A punched card is a paper designed to hold digital data. 

Though now obsolete, these were among the earliest forms of computer data storage and reached their peak usage in the mid-twentieth century.

The cards contain numbered rows and columns with each cell representing a binary unit. Specialized keypunch keyboards were used to record data on the cards and tabulating machines were used to read and summarize the data. A typical computer program of the era might consist of a deck of these cards.

The process of using punched cards was widely developed by Herman Hollerith while at MIT. The technology successfully reduced the processing time of the 1890 US census by 2 years and was subsequently used by census bureaus in countries around the world.

Hollerith founded the Tabulating Machine Company in 1896; we now know this company as IBM (International Business Machines Corp.) Several decades after developing the technology, punched cards were so widely used in industry and government that IBM was printing 10 million new cards everyday.