There are many topics that are not covered in the book. First, networks may be weighted, directed or signed. Then networks may exhibit structures other than those considered in the book, such as hierarchical structures, or have edges of different types, and collections of networks may arise as snapshots of a network process evolving in time. Each of these settings requires different methods of analysis. Then relationships may be expressed in more intricate ways; `edges’ may link more than just two objects, as in a hypergraph, and abstract simplicial complexes can be thought of as higher dimensional analogues of geometric graphs. These, and other topics, are sketched in this chapter. The material in this book forms a general basis that can be used in coming to grips with these more advanced settings.