A credential allows CDP to authenticate with your cloud provider account and obtain authorization to provision cloud provider resources on your behalf.
The authentication and authorization process varies depending on the cloud provider, but is typically done by assigning a specific role (with a specific set of permissions) that can be assumed by CDP, allowing it to perform certain actions within your cloud provider account.
A credential is a core component of an environment, providing access to the region and virtual network that make up the environment and allowing CDP to provision resources within that environment. Credentials are managed separately from environments, because you can reuse the same credential across multiple environments if needed. For example, the following diagram presents a scenario where one credential (credential A) is used by a single environment (cloud provider environment 1) but another credential (credential B) is used by multiple environments (cloud provider environment 2 and 3). In this case, it is implied that cloud provider environment 2 and 3 must represent the same AWS or Azure account, but can correspond to different regions and/or VPCs/subnets.