Location-based social networks (LBSNs) are mobile applications that allow people to share their physical location with friends through their mobile device. The sharing of location is a relatively new form of computer-mediated communication, and there is a lack of existing research examining the coor- (2011) show, newer mobile applications are often built around the importance of physical location. These applications, commonly referred to as location-based services, use the location-aware capabilities of newer mobile phones to provide people with information about their surroundings. The information these applications provide includes locations of historical sites, restaurant reviews, and geotagged narratives about specific locations. Increasingly, individuals also use mobile applications to share their location with friends. Mobile applications that allow for social location sharing are called location-based social networks (LBSNs), and they are a growing subset of location-based services.With the growth of location-aware mobile applications, people are increasingly able to share their location in multiple ways, whether through check-ins on popular LBSNs like Foursquare, geotagged tweets, or geotagged photos on Flickr. To further our understanding of the social sharing of location information, this study provides a theoretically and qualitatively grounded examination of the mobile communication practices of Foursquare users. The data reported in this study is drawn from 36 interviews of frequent Foursquare users and focuses on two independent yet interrelated areas: the role physical location plays in the coordination practices of Foursquare users and the different ways in which * Accepted by previous editor Maria Bakardjieva Foursquare users interpret the meaning of the application. Now that over 50% of adults in the United States own location-aware smartphones (Smith, 2013), it is important for researchers to develop frameworks for understanding how the addition of physical location to mobile communication may impact social practices. This study helps develop a framework that will be valuable for future social scientific approaches to location-based services in two significant ways. First, I show that to understand how people use LBSNs, we must understand the physical spaces in which they use the applications. Unlike with text messaging or voice calls, understanding the location of users is necessary for analyzing why they share their location and whether they use their location to coordinate with others. Secondly, this article introduces a heuristic framework for understanding the different ways people use applications like Foursquare. The data reported here reveals four primary types of Foursquare users, and this taxonomy of users can be useful for future research seeking to develop and test hypotheses of usage patterns. In addition, this article shows how these different uses complicate Foursquare's utility as a tool for mobile coordination because people cannot be sure why others are sharing their location...