Embodiments for implementing public and private geo-fences are generally described herein. A system comprises a geo-fence server adapted to: receive geographical coordinates of a device; determine that the device is located in a geo-fence; determine a type of the geo-fence; and transmit a notification to the device based on the type of the geo-fence. A mobile device for using person-to-person geo-fences is adapted to: receive a geo-fence object; store the geo-fence object at the mobile device; subsequent to storing the geo-fence object, obtain a geographical position of the mobile device; determine whether the mobile device is located in a geo-fence based on the geographical position; determine whether the geo-fence object is associated with the geo-fence; and present the geo-fence object when the geo-fence object is associated with the geo-fence.