The internet and online social networks have resulted in dramatic changes in the information landscape. Pessimistic views fear that networks and algorithms can limit exposure to various content by exposing users to pre-existing beliefs. In this respect, coordinated campaigns can amplify these individuals' voices above the crowd, capable of hijacking conversations, influencing other users and manipulating content dissemination. Through a systematic literature review, this chapter locates and synthesises related research on coordinated activities to (i) describe the state of this field by identifying the patterns and trends in the conceptual and methodological approaches, topics and practices; and (ii) shed light on potentially essential gaps in the field and suggest recommendations for future research. Findings show an evolution of the approaches used to detect coordinated activities. While bot detection was the focus in the early years, more recent research focused on using advanced computational methods based on training datasets or identifying coordinated campaigns by timely and similar content. Due to the data availability, Twitter is the most studied online social network, although studies have shown that coordinated activities can be found on other platforms. We conclude by discussing the implications of current approaches and outlining an agenda for future research.