ProSUM - Latin for “I am useful” - aims to provide better information on raw materials from secondary origins. It focuses in particular on the content of Critical Raw Materials (CRMs) from Batteries (BATT), Waste Electrical and Electronic Equipment (WEEE), End of Life Vehicles (ELV) and Mining Wastes (MIN) available for processing in Europe. However, data for these products are usually very scattered amongst a variety of institutions, including government agencies, universities, NGOs and industry. This deficit is addressed in this H2020 funded project. ProSUM will establish a European network of expertise on secondary sources of CRMs, vital to today's high-tech society. It coordinates efforts to collect secondary CRM data and collate maps of stocks and flows for materials and products in the “urban mine”. The project will construct a comprehensive inventory identifying and mapping CRM stocks and flows across the European Union (EU). Via a user-friendly, open-access Urban Mine Knowledge Data Platform (EU-UMKDP), it will combine and relate them to primary raw materials data from the EU-FP7 Minerals4EU project and communicate the results online through the future European Geological Data Infrastructure (EGDI) at large. It will also provide update protocols, standards and recommendations to maintain and expand the EU-UMKDP in the future.