bug

Bug is a term used in multiple contexts. In information technology, a bug is an unintended defect in software, firmware, or hardware that causes incorrect results, failures, or security vulnerabilities. The process of fixing bugs is debugging, and tracking bugs is a standard part of software development.

In everyday language, bug also refers to insects. In biology, true bugs are members of the order Hemiptera. The word has historical use in engineering long before computing; in computing, its popular association comes from Grace Hopper’s work in the 1940s, when a moth was found in a relay of the Harvard Mark II, leading to the phrasing of a discovered bug.

Common software bugs include syntax errors, logic errors, runtime errors, off-by-one errors, concurrency issues, and performance or security defects. Causes range from unclear requirements and ambiguous interfaces to miscommunication, rushed timelines, or environmental differences between development and production. Bugs are typically investigated by attempting to reproduce them with documented steps, which helps in isolating a root cause.

The bug lifecycle usually proceeds from discovery to reproduction, isolation, patching, testing, and deployment. Developers use debugging tools, code reviews, and automated tests to identify and fix defects, and bug-tracking systems organize issues with identifiers, severity, priority, and status.

Insects popularly called bugs include many small arthropods; while not all are true bugs, the term remains common in everyday speech. True bugs belong to the order Hemiptera. Bugs can be pests (such as bed bugs or aphids) or beneficial (predatory or pollinating species); management approaches range from cultural practices to chemical and biological controls.