Summary: This paper is basically a tutorial on error detection and correction. The presentation though is via a new approach. This approach has an inherent characteristic leading to parallel hardware implementation and is thus better suited for computer and parallel processing applications. Codes with the desired specifications are constructed by the computer. The design of the codes is within the geometric framework of the Karnaugh map. The mathematics involved is simpler and more intuitive than the traditionally highly mathematical approach. Original results on error detection and conditions for optimal codes are obtained, optimal in the sense of leading to minimum hardware time delays.