Report on CLEF 2020

This is a report on the tenth edition of the Conference and Labs of the Evaluation Forum (CLEF 2020), (virtually) held from September 22--25, 2020, in Thessaloniki, Greece. CLEF was a four day event combining a Conference and an Evaluation Forum. The Conference featured keynotes by Ellen Voorhees and Yiannis Kompasiaris, and presentation of peer reviewed research papers covering a wide range of topics in addition to many posters. The Evaluation Forum consisted to twelve Labs: ARQMath, BioASQ, CheckThat!, ChEMU, CLEF eHealth, eRisk, HIPE, ImageCLEF, LifeCLEF, LiLAS, PAN, and Touche, addressing a wide range of tasks, media, languages, and ways to go beyond standard test collections.