A Metadata Broker is a core intermediary component of a data space that facilitates the discovery and management of metadata, specifically Self-Descriptions of Data Space resources and connectors. It acts as a registry where participants publish metadata about their data assets and services, enabling other participants to discover relevant data offerings. The broker provides indexing, querying, and search functionalities, allowing data consumers to find suitable data sources without needing prior knowledge of the providers' locations. A Dataspace Metadata Broker is a Dataspace Connector, which contains an endpoint for the registration, publication, maintenance, and query of Self-Descriptions. The Metadata Broker stores Self-Descriptions, which are structured according to the Data Space Information Model, typically encoded in formats like RDF/JSON-LD, and makes them searchable through standard interfaces. However, it does not actively transfer data between providers and consumers; it solely handles metadata. This ensures semantic interoperability and compliance with the Dataspace framework while maintaining the sovereignty of data providers over their resources. The broker itself is a specialized type of Dataspace Connector, requiring compliance with the Dataspace Connector specification to guarantee trust and security in its operations.