Geo-location, also called geotagging, is the practice of associating digital resources like photos and posts with physical locations. It uses GPS and other technologies to track "where you are right now." While early methods used things like smoke signals and compasses, modern geo-location grew from radio triangulation in 1900 and satellite GPS in 1960. Today popular apps like Foursquare, Facebook Places, and Gowalla allow users to check-in at locations and see where friends have checked-in. These apps work by using GPS, cell towers, or WiFi to determine a user's location. Marketers can utilize geo-location by targeting geo-targeted pay-per-click ads, improving customer communication and