INVEST criteria
INVEST is a mnemonic — coined by Bill Wake in 2003 — for the qualities of a good user story: Independent (can be worked on without depending on other stories), Negotiable (not a rigid contract, room to discuss the implementation), Valuable (delivers value to the user or business), Estimable (the team can size it), Small (fits in a single sprint), Testable (acceptance criteria can be verified).
INVEST is the most-cited checklist in agile story-writing because the qualities are operationally testable: in refinement, the team can walk through the list for each story and reject ones that fail. The hardest in practice is Independent — stories often have technical dependencies that don't show up in the user-facing description. The most-violated is Small — teams routinely commit stories that turn out to be epics. INVEST pairs naturally with story splitting (a too-big story becomes multiple INVEST-compliant stories) and with definition of ready (stories must be INVEST-compliant to enter a sprint).
Related terms
- Story splitting
Story splitting is the practice of breaking a large user story into smaller stories that each independently deliver value.
- Definition of ready
Definition of Ready is the team's explicit checklist that a story must pass before it can enter a sprint.
- Vertical slicing
Vertical slicing is the practice of breaking work into thin slices that cut through every layer of the architecture — UI, business logic, data, infrastructure — so each slice delivers end-user value independently.