# Security Token Service (STS)

* STS is a web service that enables you to **request temporary, limited-privilege credentials for IAM users or for users that you authenticate** (federated users).

## AssumeRole <a href="#api_assumerole" id="api_assumerole"></a>

* **Returns a set of temporary security credentials that you can use to access AWS resources** that you might not normally have access to.<br>
* These **temporary credentials consist of an access key ID, a secret access key, and a security token**.<br>
* Typically, you **use `AssumeRole` within your account or for cross-account access**.<br>
* **For cross-account access**, imagine that you own multiple accounts and need to access resources in each account, you can **create one set of long-term credentials in one account and then use temporary security credentials to access all the other accounts by assuming roles in those accounts**.<br>
* By default, the **temporary security credentials created by `AssumeRole` last for one hour**.<br>
* However, you can **use the optional `DurationSeconds` parameter to specify the duration of your session**.
