No typing needed: how a grocery bill reads itself

At the till, the cashier never types the price of your chips. A red light sweeps over the zebra-striped lines on the packet, and the price just appears. Nobody typed anything.

This is data entered indirectly: the source itself — a bar code, a cheque, a bubble sheet — carries data that a machine reads directly, without a human retyping it. These are source data-entry devices.