Automatic cookie single sign on on multiple domains - like google

Question

I don\'t understand how google achieve the following mechanism of single sign on:

1. I login in gmail for example (I suppose this creates a cookie withmy authorizatio

Answer 1

As far as I remember, if I am not wrong, cookies contains a specified field that contains the domain that can read and get such cookie. That is made in order to prevent certain web sites to read all your cookie list and make your own business. You should be able to see which kind of sites can 'see' your gmail cookie.

Correct me if I am wrong, this should compile the answer given regarding the SID and gmail-YouTube example..