What is a bug? 🐛

As mentioned initially: It is something not working as expected. It can fail on any aspect of a feature:

Behavior: we need to refine our design.
Usability: The feature cannot be accessed properly
- A delete button hidden under an overlay
- An API route not responding.
Compatibility: feature does not work on a certain platform we are supposed to support.
- it works on Chrome but not Firefox.
- it works on Node.js v22 but not v18.
Performance: the team list is taking 30s to load.
Security: Someone managed to inject SQL 😱.

And finally, let’s add a final one:

Defects – feature-unrelated

Those are developer mistakes or infrastructure issues:

Syntax errors at runtime, like TypeError
DB cannot connect