Geo-fencing is a technology that allows creating a virtual boundary around a physical location, using GPS, RFID, Wi-Fi, cellular data, or other methods. Geo-fencing can be used for various purposes, such as triggering an action, sending a notification, collecting data, or providing a service, when a device or an object enters or exits the geofenced area. Geo-fencing has many applications in different domains, such as warehouse, security, transportation, health care, education, and entertainment. In this paper, we will explore the concept of geo-fencing, how it works, what are its benefits and challenges, and what are some of the current and future use cases of geo-fencing.