In the offline world, getting to know new people is heavily influenced by people’s physical context, that is, their current geolocation. People meet in classes, bars, clubs, public transport, and so on. In contrast, first-generation online social networks such as Facebook or Google+ do not consider users’ context and thus mainly reflect real-world relationships (e.g., family, friends, colleagues). Location-based social networks, or second-generation social networks, such as Foursquare or Facebook Places, take the physical location of users into account to find new friends. However, with the increasing number and wide range of popular platforms and services on the Web, people spend a considerable time moving through the online worlds. In this article, we introduce cyber-physical social networks (CPSN) as the third generation of online social networks. Beside their physical locations, CPSN consider also users’ virtual locations for connecting to new friends. In a nutshell, we regard a web page as a place where people can meet and interact. The intuition is that a web page is a good indicator for a user’s current interest, likings, or information needs. Moreover, we link virtual and physical locations, allowing for users to socialize across the online and offline world. Our main contributions focus on the two fundamental tasks of creating meaningful virtual locations as well as creating meaningful links between virtual and physical locations, where “meaningful” depends on the application scenario. To this end, we present OneSpace, our prototypical implementation of a cyber-physical social network. OneSpace provides a live and social recommendation service for touristic venues (e.g., hotels, restaurants, attractions). It allows mobile users close to a venue and web users browsing online content about the venue to connect and interact in an ad hoc manner. Connecting users based on their shared virtual and physical locations gives way to a plethora of novel use cases for social computing, as we will illustrate. We evaluate our proposed methods for constructing and linking locations and present the results of a first user study investigating the potential impact of cyber-physical social networks.