Each request to an API that is represented in the Google Developers Console must include a unique identifier.
Unique identifiers enable the Developers Console to tie requests to specific projects in order to
Google supports two mechanisms for creating unique identifiers:
For applications that use the OAuth 2.0 protocol to call Google APIs, you can use an OAuth 2.0 client ID to generate an access token. The token contains a unique identifier.
An API key (either a server key or a browser key) is a unique identifier that you generate using the Developers Console. Using an API key does not require user action or consent. API keys do not grant access to any account information, and are not used for authorization.
Use an API key when your application is running on a server and accessing one of the following kinds of data:
Casiano Rodriguez León 2015-01-07