Patterns and processes emerge unbidden in complex systems when many simple entities interact. This overview emphasizes the role of networks in emergence, notably network topology, modules, motifs, critical phase changes, networks of networks and dual-phase evolution. Several driving mechanisms are examined, including percolation, entrainment, and feedback. The account also outlines some of the modelling paradigms and methods used to study emergence, and presents cases to show how emergence occurs, and its implications in economics and other real-world contexts.