[jakub_g]

WebRTC can also be used for fingerprinting (apparently Chrome only) in a similar way as cookies. [1] has an explanation and test of it, as well some other fingerprinting methods.

[1] https://www.browserleaks.com/webrtc#webrtc-device-id

[juberti]

These ids work just like cookies; scoped to each user and origin. If you clear cookies, the ids are cleared as well.