Interactions between Facebook users hold important and valuable information. Analyzing activity networks modeled based on users' interactions can be used in different fields such as community detection, influence analysis, activity prediction, and spam detection. In this book, we study different Facebook activity networks like, comment, post, share, and mixed as the mixture of the previous three. We first present the data collection process and high level analysis of these networks. Then we study different structural characteristics of various activity networks. After that the macroscopic and microscopic evolution of Facebook activity networks over time is presented. Finally, we study influential users in activity networks. The results show that different Facebook activity networks have different characteristics.