Cross domain cookies - it must be possible [duplicate]

Question

Possible Duplicate:
cross domain cookies

If i understand correctly, it is not possible to save cookies for different domains: only sub domains of the same root.

However, when looking on some sites, i see this happening.

The most obvious example is on youtube where there are cookies for youtube.com and google.com present.

How is this possible? How are they achieving this?

Answer 1

If for example youtube.com includes an image from google.com, then google.com can place cookies "on the page". The individual cookie is not shared between domains.

See for example this answer for more information on how this can be achieved: Cross domain cookies