The characteristics working group included Muki Haklay, Alice Motion, Bálint Balázs, Barbara Kieslinger, Bastian Greshake Tzovaras, Christian Nold, Daniel Dörler, Dilek Fraisl, Dorte Riemenschneider, Florian Heigl, Fredrik Brounéus, Gerid Hager, Katja Heuer, Katherin Wagenknecht, Katrin Vohland, Lea Shanley, Lionel Deveaux, Luigi Ceccaroni, Maike Weisspflug,, Margaret Gold, Marzia Mazzonetto, Monika Mačiulienė, Sasha Woods, Soledad Luna, Susanne Hecker, Teresa Schaefer, Tim Woods and Uta Wehn. The development of these characteristics was supported by European Union's Horizon 2020 research and innovation programme under grant agreement No. 824580, project EU-CiƟzen.Science (The Platform for Sharing, Initiating, and Learning Citizen Science in Europe), the ERC Advanced Grant project European Citizen Science: Analysis and Visualisation (under Grant Agreement No 694767). Thanks to the Bettencourt Schueller Foundation long term partnership ,this work was partly supported by CRI Research Fellowships to Muki Haklay, Alice Motion, and Bastian Greshake Tzovaras.

This explanation document provides an interpretation of and explanation for the characteristics document, which was kept short to make it useful to different stakeholders. In this document, the characteristics document is represented, with the original text in blue and an explanation in black. The research article describing this work 'Contours of citizen science: a vignette study' can be found in the Royal Society Open Science journal at https://doi.org/10.1098/rsos.202108.