Definition
An IAM policy is a JSON document that defines permissions for an identity, such as a user or group, within a cloud computing environment. It specifies what actions an identity can perform on which cloud resources and under what conditions. In practice, these policies are attached to IAM principals to grant or deny access, ensuring that users and applications only have the necessary privileges to perform their intended functions. Understanding IAM policies is crucial for maintaining security and operational efficiency by preventing unauthorized access and accidental data modification. For instance, a policy might allow a developer to read from a specific database but prevent them from deleting it. This differs from an IAM role, which is an identity with specific permissions that an assumed user or service can use temporarily. IAM policies are fundamental to cloud security domains and appear on exams like AWS Certified Solutions Architect Associate and CCSP.