Platform-hosted crowds grow fast in number, variety, and socio-economic importance. Extant literature focuses on subsets of platform-hosted crowdshence its lack of generalizability and relies on traditional governance concepts (i.e. market, organization and community) that failed to capture platform-hosted crowds. We suggest defining platform-hosted crowds in terms of large numbers of actors with digital identities, specific purposes reflected in purpose-specific digital infrastructures (i.e. exchange platforms), and host organizations providing platforms and orchestrating co-organizers. Specifying elementary exchange modes and types of content-to-be-ex- changed, we develop a typology of platform-hosted crowds. In doing so, we propose steps towards a conceptual language capable of capturing all platform-hosted crowds and advancing our understanding of markets, organizations and communities by viewing them as instantiations of crowd.