Advertisers may also deliver ads based on a user's suspected geography through geotargeting. A user's IP address communicates some geographic information (at minimum, the user's country or general region). The geographic information from an IP can be supplemented and refined with other proxies or information to narrow the range of possible locations. For example, with mobile devices, advertisers can sometimes use a phone's GPS receiver or the location of nearby mobile towers. Cookies and other persistent data on a user's machine may provide help narrowing a user's location further.
You may use both cash or non-cash incentives for referral marketing example, but a Chicago University study found that non-monetary incentives were more effective than cash benefits by 24%. It is also better to not confine referral to customers or employees alone, referral marketing websites can also be used to new customers and lure them into referral marketing programs.