Geo-social networking allows people to share their geographic locations through social networks. Popular geo-social networks like Foursquare let users check-in at locations and collect badges, while also linking to Twitter. These networks raise privacy concerns but provide benefits like knowing what friends are doing and finding recommendations. Geo-social networking growth has been massive and built-in GPS will expand it further, while networks like Facebook have also introduced location-sharing features. Questions remain around privacy and how personal information shared can be used.