P3P and Google's cookies
In some situations, the cookies we use to secure and authenticate your Google Account and store your preferences may be served from a different domain than the website you're visiting. This may happen, for example, if you visit websites with Google +1 buttons.
Some browsers require third party cookies to use the P3P protocol to state their privacy practices. However, the P3P protocol was not designed with situations like these in mind. As a result, we've inserted a link into our cookies that directs users to a page where they can learn more about the privacy practices associated with these cookies.
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Kaley is on the Accounts support team and author of this help page. Please leave suggestions below on how to improve her article.