This chapter introduces some technical details about networks. Although they may seem like a complication that could be saved for later, the details presented here are actually a useful starting point. They will provide a sense of the many options for ways that a network can matter, which is helpful to have in mind when constructing a theory that will guide data collection. A social network is a record of a set of relationships – links – among actors in a group of interest. Depending on which relationships are present, an individual may find herself in a very different network position than someone else. Different groups can have different patterns of relationships, which means there can also be variation across networks. This chapter will help us be precise in these comparisons across actors and across networks and will highlight why they can be relevant to empirical research.