How is geolocation done?

Every device connecting to the internet must bare an unique IP address, kind of telephone number, to be identified to communicate with other devices on the internet. On the other hand, the actual assignment of an address is not arbitrary, which is governed by the Internet Registry (IR) Hierarchy system with the Internet Assigned Numbers Authority (IANA) sitting on the most top level and several Regional IRs sitting under to operate in large geopolitical regions such as continents and countries. Such a hierarchy allocation allows for easy detection of nation, sometimes region, simply by looking at the registrar's location information. If such an attempt fails to retrieve any specific information, a further lookup at the registered organization, typically an Internet service provider (ISP), should be accurate enough to get the country information.

What is geolocation used for?

While targeting contents to the specific visitors who view the site is the major use, among the others are:

• Location-awareness applications (GPS, Chat, Helpdesk, etc.);
• Spam filtering;
• Traffic balancing among locations;
• Web log statistics and analysis;
• Fraud detection;
• Online geo-targeting campaign.

To feed the need for finer information about geolocation, several approaches have been employed and all efforts turn to establish their own massive mapping databases and the accuracy varies. Here are a list (*) of geolocation projects or products.

(to be added..)

Note(*): The list will be updated periodically but an immediate access of this growing list can always be found here.