Bug
ELI5 — The Vibe Check
A bug is anything in your code that makes it behave wrong. The word comes from 1947 when an actual moth got stuck in a computer relay and caused a malfunction. Today a bug can be a typo, a wrong calculation, a misunderstood requirement, or just bad luck. Finding and killing bugs is half the job.
Real Talk
A bug is a defect in software that causes it to produce incorrect results or behave unexpectedly. Bugs are categorized by type (syntax, runtime, logic, concurrency, UI) and severity (critical, major, minor). Bug tracking systems (Jira, GitHub Issues, Linear) manage bug reports through lifecycle states: open, in-progress, fixed, verified.
Show Me The Code
// The original bug — from Grace Hopper's log, Sept 9, 1947:
// "First actual case of bug being found"
// (A moth was found in the Mark II computer relay)
// Modern bug example:
function isAdult(age) {
return age > 18; // BUG: should be >= 18
} // 18-year-olds incorrectly rejected
When You'll Hear This
"File a bug report for this." / "I found a bug — it calculates the discount incorrectly for premium users."
Related Terms
Debug
Debugging is the process of finding and fixing the gremlins in your code. Something is broken, and you need to play detective — adding clues (console.
Error
An error is when your program says 'I cannot do that' and either stops or complains loudly. It is the computer's way of telling you something went wrong.
Hotfix
A hotfix is an emergency patch you ship immediately to fix a critical bug in production — no waiting for the next planned release.
Logic Error
A logic error is the sneakiest kind of bug — the code runs perfectly fine, no crashes, no errors, but it does the WRONG thing.
Technical Debt
Technical debt is the coding equivalent of putting things on a credit card.