Whether you are hitting the Content Fetch REST API over HTTP directly or through an SDK, you'll need to know a few things about your instance in order to authenticate your requests.
API URL - This is the URL where your API requests will be sent to. Some client SDKs, such as the Content Fetch JS SDK will resolve this automatically for you.
GUID - This is your instance's unique identifier.
API Key - This is your secret API Key used for authentication that must be included in the header for each REST API request. You can create as many API Keys as you see fit. API Keys may also have an optional expiry date.
There are two types of API Keys, one for viewing published (live) content and the other to view the latest content.
Type=Content Fetch - when using this API Key, only Published content will be returned by the Content Fetch API.
Type=Content Preview - when using this API Key, All the latest content will be returned by the Content Fetch API, regardless of whether it is in Staging or Published