Using AWS Identity and Access Management (IAM) to grant users only the permissions required to perform a task is known as:

The principle of least privilege access dictates that users, programs, or processes should be granted only the essential permissions needed to perform their intended function, and no more. This minimizes the potential damage from accidental errors, malicious activity, or compromised credentials. For example, a user who only needs to read data from an S3 bucket should not be granted write or delete permissions. Restricted access is a general term that could encompass various security measures, but it's not the specific principle. As-needed access is similar but less precise than "least privilege," which emphasizes the minimum necessary permissions. Token access refers to using temporary, cryptographically signed credentials for authentication, which is a different security concept.