Task
The atomic unit of work in BPMN: one activity, one actor, one outcome, not decomposable in this diagram.
What a task is
A task is the smallest activity in BPMN: a single step that the diagram does not decompose further. It is drawn as a rounded rectangle, usually with a text label describing what happens ("Review request", "Send email", "Calculate total"). A task is atomic at the level of this diagram. It might be further refined in a different diagram, but here it is the unit of work.
A plain task has no marker; its performer is unspecified. BPMN 2.0 also defines typed tasks that surface what kind of work is being done: a *user task* (person in the loop), a *service task* (automated), a *script task* (code), a *business rule task* (decision engine), a *send task* or *receive task* (message I/O). Typed tasks carry a small icon in the upper-left corner.
The granularity choice
Choosing how granular to make a task is the single biggest modelling decision in BPMN. Too coarse and the diagram hides where work actually happens ("Do onboarding" as one task is useless). Too fine and the diagram becomes noise ("Click the submit button" is not worth a task). A useful heuristic: one task per owner per verb phrase. If you need "and" in the label, it is two tasks; if the task could be delegated to a different team without a handoff, it is one.
Tasks in LucidFlow
Every task LucidFlow generates carries three KPIs (estimated duration, estimated cost per execution, and frequency) pre-populated from patterns in the source document. The ESSII framework evaluates each task against five axes: can it be eliminated, simplified, standardised, integrated, or intelligized? The target BPMN (the AI-transformed process) often shows a plain task replaced by a typed task (user → service) to visually capture that a job crossed the automation boundary.
Frequently asked questions
What is the difference between a task and an activity?
A task is a specific kind of activity, the atomic one. Sub-processes and call activities are also activities. Every task is an activity, but not every activity is a task.
Do typed tasks add execution behaviour?
On a BPMN engine, yes. A user task creates a work item in a task list; a service task invokes a web service; a script task runs code. On a documentation diagram, the type is purely descriptive.
How many tasks should a typical process have?
A clean top-level process has 10–20 tasks. More than 30 at one level usually means the diagram is under-decomposed, time to extract sub-processes. Fewer than 5 usually means the diagram is over-summarised.