A patch is a set of changes to a computer program or its supporting data designed to update or repair it. This includes bugfixes or bug fixes to remove security vulnerabilities and correct bugs (errors). Patches are often written to improve the functionality, usability, or performance of a program. The majority of patches are provided by software vendors for operating system and application updates.
A program tape for the 1944 Harvard Mark I, one of the first digital computers. Note physical patches used to correct punched holes by covering them.
A software bug is bug in computer software.
Error resulting from a software bug displayed on two screens at La Croix de Berny station in France