Sources are connections to third-party APIs that you want to integrate with. They usually carry developer credentials, such as a
Fiber helps you build powerful product integrations with a growing number of SaaS apps, as you can see in our sources catalog page. Sources usually carry developer such as client IDs and client secrets, required by Fiber to interact with the third-party API.
Finally, syncs connect sources to destinations. Each sync can only be attached to one source and one destination, but you can create as many syncs as you would like.
Fiber's goal is to power integrations between your product and third-party SaaS tools. So Fiber needs the credentials that you use to power third-party accounts.