Mozilla is offering an experimental add-on to its Firefox browser, which illustrates technique tracking graphically as the user moves between sites

Collusion is part of Mozilla's work with the Ford Foundation to inform people about the privacy aspects of cookies and browser tracking. It creates a spider-style plans of tracking as the user goes between sites.

A demo of the software reveals how users are tracked between two websites that share an advertiser.

The add-on will allow individuals to see who is tracking them and to convert tracking off precisely, says Mozilla.

In time, the company intends to launch a full version of Collusion and use the information it yields to build a global database of anonymous tracking information "and make it available to help researchers, journalists and others analyse and explain how data is tracked on the web", the company said in a statement.

Last month, the US government announced it will introduce a Bill of Privacy Rights, which includes backing for a do not track (DNT) feature in all browsers.

The announcement comes amid a groundswell of privacy agitation from government and privacy lobbying groups on both sides of the Atlantic.