In OAM, a collection is a group of objects typically having similar performance, availability, backup, retention, and class transition characteristics. You can use a collection to catalog a large number of objects. If these objects are cataloged separately, it could require an extremely large catalog. Every object must be assigned to a collection. Object names within a collection must be unique. However, the same object name can be used in multiple collections. Each collection belongs to only one Object storage group. Each storage group can contain from one to many collections.