Punched card input/output

Punched card input/output is a way of processing information that was used a long time ago. It involved using physical cards that are like pieces of cardboard with holes punched in them. The holes would be in different places across the card to make a code - like a secret code. This code told a computer what information to look up or store. When the card was put into a machine, the code was read, and the computer would do what it was told. For example, a punched card might tell a computer to look up some information or to store something.