Used by Google to check if your browser is set to accept cookies as well as statistics for displaying custom ads in, among other things, Youtube videos.

No personally identifiable information is collected or passed unless you're signed in to your google account, then your choices and what you see with your account are linked so that Google can better target ads.

See also the Google Privacy Policy, as well as additional information about DoubleClick's use of cookies, which also includes information about how to change your ad serving settings from Google services.

If you want to opt out of Doubleclick cookies, you can do this by installing an application from Google.