Root Cause Analysis
Root cause analysis is the process of tracing a defect back past its symptom to the actual underlying reason it happened — a missing requirement, a process gap, a misunderstanding — so the fix addresses the cause, not just the visible failure. Done well, it prevents whole categories of future defects, not just the one that got reported.
A quick fix that patches the visible failure without understanding why it happened tends to leave the actual fault-producing conditions in place, ready to cause a similar bug somewhere else. Root cause analysis pushes past "what broke" to "why did our process allow this to happen" — techniques like the "5 Whys" (repeatedly asking why until you stop getting a new answer) are a common lightweight way to do this.
It's most valuable after a significant incident or a recurring class of defects, not every single bug — the cost of a full root cause analysis needs to be worth the prevention value. When it is done, the output should be an action, not just a diagnosis: a new test case, a process change, or a code review checklist item that keeps the same class of defect from recurring.
