BPMN Symbols and Notation Reference
Complete guide to BPMN 2.0 symbols — tasks, gateways, events, pools, lanes, and message flows. Learn what each symbol means, when to use it, and how it fits into a professional process diagram.
What Is BPMN?
Business Process Model and Notation (BPMN) is the international standard for process diagrams, maintained by the Object Management Group (OMG). BPMN 2.0 provides a shared visual language that business analysts, developers, and stakeholders can all understand. Unlike ad-hoc flowcharts, BPMN diagrams are precise enough to be executed by process engines yet readable enough for non-technical audiences.
The standard defines four categories of symbols: flow objects (tasks, events, gateways), connecting objects (sequence flows, message flows, associations), swimlanes (pools and lanes), and artifacts (data objects, text annotations, groups). The sections below cover the most commonly used symbols in each category.
Task Symbols
Tasks are the basic units of work in a BPMN diagram. Each task type communicates how the work is performed — whether by a person, a system, or a combination of both. Understanding the differences helps you create diagrams that accurately describe your organization's workflow.
User Task
Represents work performed by a human with the assistance of a software application. Use user tasks for activities that require a person to interact with a system, such as filling out a form, reviewing a document, or approving a request. User tasks are the most common task type in business process diagrams because most real-world workflows involve people working with software.
When to use: Use when a person interacts with a system to complete the step.
Service Task
Represents automated work performed by a system or web service without human involvement. Service tasks are used for steps like sending an automated email, calling an API, running a database query, or performing a calculation. They are the building blocks of process automation and are essential for modeling end-to-end workflows that include both human and machine steps.
When to use: Use for fully automated steps — API calls, system integrations, background jobs.
Manual Task
Represents work performed entirely by a person without any software assistance. Manual tasks cover physical activities like delivering a package, conducting an in-person interview, or performing a physical inspection. These tasks cannot be managed or tracked by a workflow engine because they happen outside any system.
When to use: Use for physical work done without a computer or application.
Script Task
Represents a task executed by a process engine using a defined script. Script tasks are used when a workflow engine runs a piece of code, such as a business rule calculation, data transformation, or variable assignment. Unlike service tasks, script tasks run inside the engine itself rather than calling an external service.
When to use: Use for inline logic executed by the workflow engine, not external systems.
Event Symbols
Events represent something that happens during a process. They are categorized by position (start, intermediate, end) and by trigger type (message, timer, error, signal, and more). The circle shape and border weight tell you at a glance where you are in the process lifecycle.
Start Event
Marks the beginning of a process flow. Every process must have at least one start event. A plain start event (no icon inside) is a "none" start event, meaning the process is triggered manually or by an unspecified mechanism. Start events with internal icons represent specific triggers: a clock icon for timer start events (process starts at a scheduled time), an envelope icon for message start events (process starts when a message arrives), and a signal icon for signal start events (process starts when a broadcast signal is received).
When to use: Place one start event at the top or left of each pool. Add a trigger icon only if the trigger type matters to readers.
Intermediate Event
Represents something that happens during the process, between the start and end. Intermediate events can be "catching" (waiting for something to happen, like receiving a message or a timer expiring) or "throwing" (producing an output, like sending a message or raising a signal). When attached to the boundary of a task, an intermediate event models an interruption or timeout — for example, a timer boundary event on an approval task that escalates if no response is received within 48 hours.
When to use: Use catching intermediate events for waits and delays. Attach boundary events to tasks for timeouts and escalations.
End Event
Marks the completion of a process path. A process can have multiple end events representing different outcomes — for example, "Order Fulfilled" and "Order Cancelled." A plain end event terminates the current path. A terminate end event (filled circle inside) ends the entire process instance immediately, cancelling all remaining activities. A message end event (filled envelope inside) sends a message to another participant when the process ends.
When to use: Label end events with the outcome they represent, such as "Approved" or "Rejected."
Gateway Symbols
Gateways control the divergence and convergence of sequence flows. They determine which paths the process follows based on conditions, events, or parallelism. The internal marker inside each diamond tells you the routing rule at a glance.
Exclusive Gateway (XOR)
Routes the process along exactly one of several paths based on a condition. When the flow reaches an exclusive gateway, only one outgoing path is followed — the first whose condition evaluates to true. A default path (marked with a slash) is taken when no other condition is met. Exclusive gateways are the most common gateway type and correspond to "if/else" logic. They also merge multiple incoming paths back into one, allowing the process to continue once any single incoming path completes.
When to use: Label each outgoing sequence flow with the condition, such as "Amount > $5,000" or "Approved = Yes."
Parallel Gateway (AND)
Splits the flow into multiple concurrent paths that all execute simultaneously, or synchronizes multiple paths back into one. When used as a split (fork), every outgoing path is activated at the same time without conditions. When used as a join (synchronization), the process waits until all incoming paths have completed before continuing. Parallel gateways are used whenever steps can happen at the same time, such as "Send notification" and "Update database" running concurrently.
When to use: Pair every parallel split with a parallel join downstream to synchronize the paths before they converge.
Inclusive Gateway (OR)
Routes the flow along one or more paths based on conditions. Unlike an exclusive gateway (which follows exactly one path), an inclusive gateway activates every path whose condition is true, allowing multiple branches to run in parallel. When used as a join, it waits for all active incoming paths to complete. Inclusive gateways are useful when multiple outcomes can apply simultaneously, such as "Needs legal review" and "Needs compliance review" both being true for the same request.
When to use: Use when multiple conditions can be true at the same time and you need all applicable paths to execute.
Pools, Lanes, and Artifacts
Swimlanes organize tasks by participant, while artifacts provide additional context without affecting the process flow. Connecting objects like sequence flows and message flows link everything together to tell the full story of how work moves across teams.
Pool
Represents a major participant in the process, typically an organization, department, or external party. Each pool contains its own sequence flows and cannot share sequence flows with other pools. Communication between pools happens through message flows (dashed lines with open arrowheads). A collapsed pool (no visible internal elements) represents an external party whose internal process is unknown or out of scope.
When to use: Use separate pools for each organization or external system. Connect them with message flows, not sequence flows.
Lane
Divides a pool into sub-sections that represent specific roles, positions, departments, or systems within the same organization. Lanes help readers understand who is responsible for each task without changing the process logic. A "Manager" lane, a "Staff" lane, and an "IT System" lane within a single pool show all the internal handoffs within one organization.
When to use: Name lanes after roles (e.g., "Hiring Manager") rather than individuals to keep diagrams reusable across teams.
Data Object
Represents information or data that flows through the process, such as a purchase order, invoice, application form, or report. Data objects are connected to tasks with associations (dotted lines) to show which tasks read or produce data. They do not affect the sequence flow but provide important context about what information is needed at each step.
When to use: Connect data objects to tasks with dotted associations. Label them with the document or data name.
Text Annotation
Provides additional notes or comments about a diagram element without changing the process logic. Annotations are used to explain business rules, clarify exceptions, reference policies, or add context that does not fit in a task label. They are connected to the relevant element with an association (dotted line).
When to use: Use annotations sparingly to explain complex business rules or unusual process paths.
Connecting Objects
Sequence Flow
A solid line with a filled arrowhead that shows the order in which activities are performed within a single pool. Sequence flows connect tasks, gateways, and events into a step-by-step path.
Try this elementMessage Flow
A dashed line with an open arrowhead and a circle at the source. Message flows connect two separate pools to show communication between different participants or organizations.
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Try the AI BPMN generatorFrequently asked questions
What are the main categories of BPMN symbols?
BPMN symbols fall into four categories: flow objects (tasks, gateways, events), connecting objects (sequence and message flows), swimlanes (pools and lanes), and artifacts (data objects, annotations).
What is the difference between a pool and a lane?
A pool represents a major participant or organization. Lanes subdivide a pool by role or department. Message flows connect pools; sequence flows connect elements within a single pool.
How many gateway types are there in BPMN?
BPMN 2.0 defines five gateway types: exclusive (XOR), inclusive (OR), parallel (AND), event-based, and complex. Exclusive, inclusive, and parallel are the most commonly used.
What is the difference between start and end events?
A start event (thin circle) marks where a process begins with no incoming flows. An end event (thick circle) marks where a process terminates with no outgoing flows.
Can I generate a BPMN diagram automatically?
Yes. BA Copilot generates BPMN 2.0 diagrams from plain-text descriptions. The AI selects the correct symbols automatically based on your process description.
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