This lesson is the third in a three-part series on networks. In this lesson, we move beyond a focus on ecological relationships alone, as in Part 1, or simply on social relationships, as in Part 2, to introduce network concepts associated with fully coupled socio-environmental networks. This lesson covers some basics on network metrics, motifs, and multiplex networks and uses a study on illegal trafficking of wildlife species to illustrate why network analysis can be useful in managing natural resources.