BPMN Symbols Reference: Events, Activities, Gateways, and Flows

The BPMN specification defines a large catalog of symbols, and their precision is exactly what makes the notation valuable - but it also makes the symbol set intimidating at first. The trick is to see the structure behind it. Every BPMN element belongs to one of a few categories, and once you know the categories, an unfamiliar symbol is easy to place and interpret. This reference walks through those categories in the order they matter.

Use this alongside a real diagram rather than trying to memorize it. When you are modeling in the BPMN tool at /diagram-tools/bpmn-tool or the editor at /diagrams and you need to represent a wait, a decision, or a handoff, come here to confirm the correct shape. For the broader question of how to structure a whole process, the complete BPMN guide is the companion piece.

Events: circles that mark what happens

Events are drawn as circles and represent something that happens during a process. The circle's border tells you when: a thin single line is a start event, a thin double line is an intermediate event that occurs mid-process, and a thick single line is an end event. This border convention is worth memorizing because it lets you read any event's role at a glance before you even look at the icon inside it.

The icon inside the circle specifies the trigger or result. A blank event is generic; an envelope is a message event (something received or sent); a clock is a timer event (a wait or a scheduled trigger); a lightning bolt is an error event. So an intermediate event with a clock means "wait here until a time or duration," while an end event with an envelope means "the process ends by sending a message." Combining border and icon gives you a precise vocabulary for the many ways a process can begin, pause, and end.

Activities and gateways: the work and the decisions

Activities are rounded rectangles and represent work performed. A plain rounded rectangle is a task, the atomic unit of work. A rounded rectangle with a small plus marker is a sub-process, a collapsed group of steps you can expand. Markers on a task indicate its type - a person icon for a human task, a gear for a service (automated) task, an envelope for a send or receive task - which tells the reader and any automation engine who or what performs it.

Gateways are diamonds and control how the flow branches and merges. An exclusive gateway, often drawn with an X, chooses exactly one outgoing path based on a condition - the process goes one way or the other, never both. A parallel gateway, drawn with a plus, splits the flow into concurrent paths that all execute, and later a matching parallel gateway joins them back together. An inclusive gateway, drawn with a circle, allows one or more paths depending on conditions. Choosing the right gateway is one of the most common places diagrams go subtly wrong, so it is worth being deliberate.

A quick-reference symbol list

Here is a compact list of the symbols you will reach for most, grouped so you can scan to the one you need.

• Start event: thin single-line circle - where the process begins; a message or timer icon shows what triggers it.
• Intermediate event: thin double-line circle - something that happens along the way, such as a wait (clock) or a received message (envelope).
• End event: thick single-line circle - where a path terminates; every path should reach one.
• Task: rounded rectangle - a single unit of work; markers show human, service, or messaging tasks.
• Sub-process: rounded rectangle with a plus - a collapsed group of steps you can expand.
• Exclusive gateway: diamond with an X - choose exactly one path based on a condition.
• Parallel gateway: diamond with a plus - split into or join concurrent paths that all run.
• Sequence flow: solid arrow - the order of steps within one participant; message flow: dashed arrow - communication between participants.

Connecting objects and swimlanes

The lines matter as much as the shapes. A solid arrow is a sequence flow and shows the order of activities within a single pool. A dashed arrow is a message flow and shows communication crossing from one participant to another. A dotted line is an association, connecting an artifact such as a data object or a text annotation to the element it describes. Mixing these up - using a sequence flow where a message flow belongs - is the fastest way to make a cross-organizational diagram wrong.

Swimlanes provide the structure that holds everything. A pool is a participant, a rounded container for everything that participant does. Lanes divide a pool by role, so each activity sits in the lane of whoever performs it. Data objects (a page shape) represent information the process reads or produces, and text annotations (a bracket with free text) let you add human explanation without affecting the flow. Together these turn a set of shapes into a model that reads clearly. Build them with correct defaults using the BPMN tool at /diagram-tools/bpmn-tool.