I work in graph theory, the mathematics of networks. A question that runs through much of my research is how much hidden structure sits inside random and random-like systems, and how randomness itself can be used to uncover order in networks that are entirely deterministic. Random graphs, for instance, turn out to behave in strikingly regular ways, and the probabilistic viewpoint has become one of the main tools for understanding networks in general. Much of my recent work concerns sparse graphs, where connections are scarce: I am interested in the weakest assumptions forcing certain patterns, such as long cycles or tree-like structures. The interplay between chance and structure sits at the heart of modern combinatorics and its connections to theoretical computer science.