Prior to joining Yahoo! Research I was an Assistant Professor at Poznan University of Technology (PUT), Poland. I received my PhD degree in 2009 and Habilitation degree in 2018, both from PUT. During my PhD studies I was mainly working on preference learning and boosting-based decision rule algorithms. During my postdoc at Marburg University, Germany, I have started working on multi-target prediction problems with the main focus on multi-label classification. Currently, my main scientific activity concerns extreme classification, i.e., multi-class and multi-label classification problems with an extremely large number of labels (hundreds of thousands and more). In recent years I have been involved in organizing several scientific events on this topic, such as a NIPS 2017 workshop (co-organized with Manik Varma and Marius Kloft), a WWW 2018 workshop (co-organized with Yahoo! Researchers: Robert Busa-Fekete, Akshay Soni, and Aasish Pappu), a ECIR 2018 tutorial (with Rohit Babbar), and a Dagstuhl Seminar in 2018 (co-organized with Marius Varma, Marius Kloft, Thorsten Joachims, and Samy Bengio). My articles have been published at the premier conferences (ICML, NeurIPS, ECML) and in the leading journals (JMLR, MLJ, DAMI) in the field of machine learning. As a co-author I won the best paper award at ECAI 2012 and at ACML 2015.