Foursquare, stylized as foursquare, is a location-based social networking website for mobile devices, such as smartphones. Users "check in" at venues using a mobile website, text messaging or a device-specific application by selecting from a list of venues the application locates nearby. Location is based on GPS hardware in the mobile device or network location provided by the application. Each check-in awards the user points and sometimes "badges".
An open source license is a copyright license for computer software that allows the source code to be freely, that is by anyone for any purpose, used, modified and shared. This allows end users to review and modify the source code for their own customization, curiosity or troubleshooting needs.