# Manage continuous deployments with versions and aliases in Step Functions
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You can use Step Functions to manage continuous deployments of your workflows through state machine *versions* and *aliases*. A *version* is a numbered, immutable snapshot of a state machine that you can run. An *alias* is a pointer for up to two versions of a state machine.

You can maintain multiple versions of your state machines and manage their deployment in your production workflow. With aliases, you can route traffic between different workflow versions and gradually deploy those workflows to the production environment.

Additionally, you can start state machine executions using a version or an alias. If you don't use a version or alias when you start a state machine execution, Step Functions uses the latest revision of the state machine definition.

**State machine revision**  
A state machine can have one or more revisions. When you update a state machine using the [UpdateStateMachine](https://docs.aws.amazon.com/step-functions/latest/apireference/API_UpdateStateMachine.html) API action, it creates a new state machine revision. A *revision* is an immutable, read-only snapshot of a state machine’s definition and configuration. You can't start a state machine execution from a revision, and revisions don't have an ARN. Revisions have a `revisionId`, which is a universally unique identifier (UUID).

**Topics**
+ [Versions](concepts-state-machine-version.md)
+ [Aliases](concepts-state-machine-alias.md)
+ [Versions and alias authorization](auth-version-alias.md)
+ [Associating executions with a version or alias](execution-alias-version-associate.md)
+ [Deployment example](example-alias-version-deployment.md)
+ [Gradual deployment of versions](version-rolling-deployment.md)