For a while I've noticed that Google logins (or, at least, GMail logins) always redirect through to "youtube.com" Is Google handling all logins from youtube.com? If so, why?
(wasn't sure if I should post this on webapps or superuser, so feel free to move this or tell me to move this to the appropriate site if necessary)
When you log into a Google site like GMail, Google also logs you into all your various accounts Google accounts - such as YouTube. In order to be logged into a site, Google sets a cookie in your browser.
This is fine for most of their properties which are on the *.google.com domain (mail.google.com, docs.google.com, etc). However a website can only set and read a cookie for it's own domain - google.com can't set a cookie for youtube.com. To get around this, as part of the login process Google will redirect you through accounts.youtube.com to log you into YouTube - and typically your country specific domain if you are outside the US (e.g. I get logged into google.com.au as well).
The full login process is described in this SO answer, it dates from 2009 but most of it should still hold true.
