Deliverable
A deliverable is a verifiable output the project produces and hands over. It is the unit a WBS decomposes around — not the activity, but what the activity leaves behind.
Activity versus deliverable
"Run user training" is an activity; "training materials and completion records" are deliverables. Activities vanish as time passes — deliverables remain and can be inspected. The principle of deliverable-oriented WBS decomposition comes from exactly this: work that leaves nothing behind offers no way to confirm it finished.
Why it matters
Deliverables are the unit of acceptance and payment. Contract payment terms hang on deliverable handover. With deliverables explicit in the WBS, "what must be handed over to close this phase" reads straight off the tree. The same holds internally: teams with clear deliverables report progress as "here is what exists," not "we worked for days."
A practical tip
Deliverables include intermediate ones — design documents, test reports, operations handover docs — anything downstream work depends on. But do not list every management byproduct like meeting minutes; the tree gets heavy. Include what acceptance or successor work actually depends on.
wbsgantt's WBS Dictionary carries a per-node deliverables field, keeping acceptance evidence attached to the tree.