Originally written in French. Translated by AI — the meaning has been preserved, not the prose.
Short definition
A gap between a piece of software's expected behaviour and its real behaviour, qualified as such by the team. It stands against no defect, which covers improvements, capability requests, misunderstandings and subjects outside priorities.
Full definition
In the normative sense, a defect is a non-conformity to a specification. In the field, it is what the team agrees to call a defect — which depends on the existence and precision of the specification, often absent.
In the articles on this blog, the word designates the result of a qualification, not an intrinsic property: it names the defect outcome of a two-branch decision. It carries no information about impact — a genuine defect can be minor, an absent capability can be blocking.
Usage in the field
Qualifying an incoming signal, upkeep of the backlog, quality metrics (regressions, defects found before production, defects found in production).
Synonyms and variants
Bug · anomaly · defect.
Not to be confused with
- Pain — what the user experiences, independent of the qualification and of the technical origin.
- Zero bug policy — the regime that forces a decision, where the defect is what you decide about.
- Improvement — an existing capability you want better, with no gap from expected behaviour.
- Capability request — a missing feature, whose absence isn't a gap but a limit of scope.
- Technical debt — a design weakness whose handling has been decided; it costs in evolution, with no visible faulty behaviour.
Examples
A button you have to click twice: a minor defect.
A legal filing the product cannot produce: not a defect, and yet more critical.
Ambiguities / debates
Without a written specification, the border between defect and improvement is negotiated case by case, often to the advantage of whoever holds the queue.
In ordinary usage, "bug" indiscriminately designates a defect in the strict sense and any annoyance a user runs into.