# Workflow Activity

> For the complete documentation index, see [llms.txt](https://docs.temporal.io/llms.txt).
> Any documentation page is available as raw Markdown by appending `.md` to its URL.

> Learn about Workflow Activities in Temporal - Activities started as a step in a Workflow, scoped to that Workflow's lifetime and recorded in its Event History.

## What is a Workflow Activity? 

A Workflow Activity is an [Activity Execution](/activity-execution) started as a step in a
[Workflow](/workflows), using the Temporal SDK from your Workflow code.

The Workflow schedules the Activity, the Temporal Service dispatches an Activity Task to an Activity
Worker polling the Activity's Task Queue, and the result is delivered back to the Workflow when the
Activity Execution closes. Each step is recorded in the Workflow Execution's
[Event History](/workflow-execution/event#event-history).

Use a Workflow Activity when you need to orchestrate multiple steps: sequencing, branching on a
result, compensating a failure, waiting on a Signal or Timer between steps. If you just need to
execute a single Activity, use a [Standalone Activity](/standalone-activity) instead.

> **💡 Tip:**
> GET STARTED
>
> Start a Workflow Activity:
> [Go](/develop/go/activities/execution)
> | [Java](/develop/java/activities/execution)
> | [PHP](/develop/php/activities/execution)
> | [Python](/develop/python/activities/execution)
> | [TypeScript](/develop/typescript/activities/execution)
> | [.NET](/develop/dotnet/activities/execution)
> | [Ruby](/develop/ruby/activities/execution)
> | [Rust](/develop/rust/activities/execution)
>

## Activity options 

You set Activity Options in your Workflow code when you schedule the Activity. At minimum, specify a
timeout - typically the [Start-To-Close Timeout](/encyclopedia/detecting-activity-failures#start-to-close-timeout).

- [Timeouts](/encyclopedia/detecting-activity-failures): Schedule-To-Start, Start-To-Close,
  Schedule-To-Close, and Heartbeat.
- [Retry Policy](/encyclopedia/retry-policies): Activities retry automatically by default, with
  exponential backoff and unlimited Maximum Attempts.
- Task Queue: routes the Activity Task to the Workers that should run it. It doesn't have to be the
  Workflow's Task Queue.

> **💡 Tip:**
> GET STARTED
>
> Set Activity timeouts and Heartbeats:
> [Go](/develop/go/activities/timeouts)
> | [Java](/develop/java/activities/timeouts)
> | [PHP](/develop/php/activities/timeouts)
> | [Python](/develop/python/activities/timeouts)
> | [TypeScript](/develop/typescript/activities/timeouts)
> | [.NET](/develop/dotnet/activities/timeouts)
> | [Ruby](/develop/ruby/activities/timeouts)
> | [Rust](/develop/rust/activities/timeouts)
>

## Event History 

A Workflow Activity writes [Activity Events](/workflow-execution/event#activity-events) to the
Workflow Execution's Event History, such as
[ActivityTaskScheduled](/references/events#activitytaskscheduled),
[ActivityTaskStarted](/references/events#activitytaskstarted), and
[ActivityTaskCompleted](/references/events#activitytaskcompleted).

Two consequences follow:

- **Replay uses the recorded result.** A completed Activity isn't executed again when the Workflow
  [replays](/workflow-execution#replay).
- **Arguments and return values are persisted.** They count toward
  [Event History limits](/workflow-execution/event#event-history-limits), so be mindful of payload
  size and of how many Activities a single Workflow Execution schedules.

## Activity Id 

A Workflow Activity's [Activity Id](/activity-execution#activity-id) is unique among the open
Activity Executions of a [Workflow Run](/workflow-execution/workflowid-runid#run-id). A Workflow Run
may reuse an Activity Id once an earlier Activity Execution with that Id has closed.

## Cancellation 

A Workflow Activity can't be canceled directly. It receives a
[Cancellation](/activity-execution#cancellation) request as a result of its Workflow being canceled,
or because the Workflow code requested it. Activities must
[Heartbeat](/encyclopedia/detecting-activity-failures#activity-heartbeat) to receive Cancellation.

The Workflow decides whether to wait for the Cancellation to be accepted or to proceed without
waiting.

## Asynchronous completion 

A Workflow Activity can return from its function without completing the Activity Execution, leaving
an external system to Heartbeat progress and deliver the final result. See
[Asynchronous Activity Completion](/activity-execution#asynchronous-activity-completion).

## Operator commands 

Pause, Unpause, Reset and Update Options let an operator intervene in a running Workflow Activity.
These commands are in [Public Preview](/evaluate/development-production-features/release-stages#public-preview).

See [Activity Operations](/activity-operations) for details.