Bug - in computer science, a word that refers to an error that manifests itself at the stage of program operation, in contrast, for example, design errors or syntax errors. Bugs can be localized and eliminated during testing and debugging of the program itself.
According to one version, this concept came into use after September 9, 1945, Harvard University scientists who tested the Mark II Aiken Relay Calculator computer found a moth stuck between the contacts of an electromechanical relay and one of the employees pronounced this term.
In fact, the word "bug" in the modern sense was used long before this case. For example, during World War II, the word "bugs" referred to problems with radar electronics.