The document discusses a content repository, which is a generic API for content storage that provides CRUD functionality as well as versioning, transactions, and search capabilities. It describes how a content repository enforces simplicity, encourages standardization, and improves scalability. Examples of content repository implementations are provided, including Apache Jackrabbit and eXo Platform. Key features of content repositories are explored such as the content model, repository structure with workspaces and nodes/properties, and node type definitions.