# Authorization

The Google PHP Client Library supports several methods for making authenticated calls to the Google APIs.

- [API Keys](api-keys.md)
- [OAuth 2.0 For Webservers](oauth-web.md)
- [OAuth 2.0 Service Accounts](oauth-server.md)

In addition, it supports a method of identifying users without granting access to make Google API calls.

- [ID Token Verification](id-token.md)