Krzysztof Ciesielski earned his PhD at one of the oldest and most prestigious university in Eastern Europe — the Jagiellonian University in Kraków — where he still works. His mathematical specialty is Topological Dynamical Systems. For nine years he served as Vice Head (responsible for teaching) of the Mathematics Institute of the Jagiellonian University. He works very actively in raising public awareness of the importance of mathematics: He is an author and co-author (mainly with Zdzisław Pogoda) of some books that became bestsellers in Poland, and for which he earned prestigious awards, including the ‘Steinhaus Prize’ and the ‘Golden Rose Prize’ for the best book for popularizing science in Poland. Since 1987 he has been a member and correspondent of the editorial board of The Mathematical Intelligencer; in 1999–2012 he was an Associate Editor of The European Mathematical Society Newsletter; since 1996 he has been a member of the Editorial Committee of the Polish monthly Delta (its Vice-Chairman since 2003); in 2007 he became a member of the editorial board of the journal Wiadomości Matematyczne of the Polish Mathematical Society and in 2018, the journal’s Editor-in-Chief. He is also involved in the organization of several mathematical competitions, including the ‘Mathematical Kangaroo’ and the ‘Polish Mathematical Olympiad’ for high school students. K. Ciesielski has been a member of the ‘Kraków Committee of Polish Mathematical Olympiad’ since 1980 (and holds its Chair since 2008). In 2018 he was elected Vice-President of the World Federation of National Mathematics Competitions.