Report on CLEF 2019

AbstractThis is a report on the tenth edition of the Conference and Labs of the Evaluation Forum (CLEF 2019), held from September 9--12, 2019, in Lugano, Switzerland.CLEF was a four day event combining a Conference and an Evaluation Forum. The Conference featured keynotes by Bruce Croft, Yair Neuman, and Miguel Martínez, and presentation of peer reviewed research papers covering a wide range of topics in addition to many posters. The Evaluation Forum consisted to nine Labs: CENTRE, CheckThat, eHealth, eRisk, ImageCLEF, LifeCLEF, PAN, PIR-CLEF, and ProtestNews, addressing a wide range of tasks, media, languages, and ways to go beyond standard test collections.CLEF 2019 marked the 20th anniversary of CLEF, which was celebrated with a dedicated session and a book on the lessons learnt in twenty years of evaluation activities and the future perspectives for CLEF.CLEF 2019 also introduced the Industry Days to further extend the reach and impact of CLEF.