Amazon CodeCatalyst is no longer open to new customers. Existing customers can continue to use the service as normal. For more information, see [How to migrate from CodeCatalyst](migration.md).

# Using predefined variables
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*Predefined variables* are key-value pairs that are emitted by a workflow automatically, and made available for you to use in workflow actions. 

For more information about variables, see [Using variables in workflows](workflows-working-with-variables.md).

**Topics**
+ [Examples of referencing predefined variables](workflows-predefined-examples.md)
+ [Referencing a predefined variable](workflows-working-with-variables-reference-output-vars.md)
+ [Determining which predefined variables your workflow emits](workflows-working-with-variables-determine-output-vars.md)
+ [List of predefined variables](workflow-ref-action-variables.md)