Mathematician Johan van Leeuwaarden (born 1978) researches the behaviour of complex networks, drawing inspiration from practical applications. For example, he studies communication networks such as the internet and logistical and social networks. In order to address issues of major social and scientific relevance, he has co-founded Data Science Center Eindhoven and the ten-year interdisciplinary programme NETWORKS, funded by the Netherlands Organisation for Scientific Research (NWO). He explains the beauty and importance of mathematics in his columns and public lectures.