However, if you choose to block or delete cookies, certain features of the Sites may not operate correctly. For further information about deleting or blocking cookies, please visit here. Information about how to opt out of the use of cookies for certain purposes (such as interest-based advertising) is discussed below in the section titled Website analytics and Interest-Based Advertising.</p> <p>Web beacons: The Sites or the emails that you receive from Vanguard use an application known as a “web beacon” (also known as a “pixel tag” or “clear gif”). A web beacon is an electronic file that usually consists of a single-pixel image.