Almost all modern browsers today support geolocation, which is the ability to track your location and by extension offer location-based services. A client-side device like an iPhone, Android device or a conventional desktop browser can retrieve geographic positioning using some JavaScript code. Asynchronous functions are implemented to allow a user to authorize applications to track his location while still making it possible to access and use the other services inside an application. The HTML 5 specification makes it possible to implement these functions using the getCurrentPosition API that is now supported by most modern browser upgrades.
Inspecting the geolocation data usually brings up a number of important details. For one, it will denote the time at which the geolocation data instance was created. A set of geographic coordinates together with their associated accuracy and other optional attributes will be displayed. Knowing this information exists will help you better determine if it is wise to allow applications to track your location or restrict access to your location. In addition, if your target device supports it, you can access some of this information and determine how you are being tracked.
For those browsers that do not support geolocation, there is always the option of using large geolocation databases to map the IP address of a device. This method however usually suffers from the fact that the IP addresses may be wrongly associated with a location, it could provide a very broad geographic area results without street or latitude/longitude locations or some addresses simply do not exist on the databases making the location untraceable. When GPs or triangulation are not available however, these external geolocation services provide a good fallback.
All in all, geolocation native on the device is considered the most accurate way of locating devices especially if they are moving and determining their speed of movement.
