Firefox and web privacy
We all know that we are being tracked on the internet when we are browsing, but we are unable to do much about it.
Many advertisers will use tracking cookies to create "fingerprints" of users in order to create advertising profiles. There may be others using the same methods to track users for more malevolent reasons.
One ironic side of preventing such "fingerprints" is that deleting them also leaves a trail - just like a black hole is observed by its effects on other things, a user may potentially also be tracked by the lack of certain types of fingerprints and different users are able to eliminate different finger prints, each user is once against trackable by their unique combination of fingerprint and lack of fingerprint.