glossary — plain english
Work breakdown structure
Usually abbreviated: WBS
The exercise of splitting a project into pieces small enough to plan — the outline you write before any chart can draw the bars.
Before a plan can have a shape, the work has to have pieces. A work breakdown structure is the splitting step: project into phases, phases into tasks, until every piece is small enough that someone can name it, own it, and guess its duration. In the formal version this is a numbered tree (1.0, 1.1, 1.2…) maintained as its own document with a dictionary attached.
The formality is optional; the thinking isn't. The WBS's real job is completeness — it's the tool that catches the work everyone forgot, the unglamorous tasks like "migrate the DNS" and "write the release notes" that sink timelines precisely because nobody wrote them down. Walking the tree top-down is how you find them before the schedule does.
For a normal-sized project, the paragraph you'd write to describe the plan — tasks, order, durations, spelled out in plain English — is the work breakdown structure, whether or not you number it. Stop breaking down when the pieces are estimable and assignable; below that line lives your to-do list, and it doesn't belong on the chart. If you want the whole method spelled out, here's how to build a work breakdown structure, step by step.
See it on a real chart
Describe your project in plain English and ganttchart.ai turns it into a shareable Gantt chart in seconds — every term on this page included. Or read the method first: the plain-English planning guide.