Web beacon

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This article is about the web tracking technique. For bugs in web software, see software bug.

A web beacon is an object embedded in a web page or email, which unobtrusively (usually invisibly) allows checking that a user has accessed the content.[1] Common uses are email tracking and page tagging for web analytics. Alternative names are web bug, tracking bug, tag, or page tag. Common names for web beacons implemented through an embedded image include tracking pixel, pixel tag, 1×1 gif, and clear gif.[2] When implemented using JavaScript, they may be called JavaScript tags.[3] There is a work in progress to standardize an interface that web developers can use to asynchronously transfer small HTTP data from the User Agent to a web server that call it simply beacons (in the context of web development) which can be used to send data to a web server prior to the loading of the document without delaying the load and affecting the perception of page load performance for the next navigation.[4]





On web pages[edit]



Tracking on web pages can be disabled using a number of techniques.

  • Turning off a browser's cookies can prevent some web beacons from tracking a customer's specific activity. The web site logs will still record a page request from the customer's IP address, but unique information associated with a cookie cannot be recorded. However, web site server techniques that do not use cookies can be employed to help track a site's cookie-blocking user. For example, a web site can identify a request from a new visitor and send that visitor links that pass a unique ID as a GET parameter.
  • Browser add-ons and extensions can be used. For example, the Ghostery add-on analyzes JavaScript to detect trackers, pixels, and beacons.[6]

In email[edit]

Web beacons are frequently used in email marketing as a way of determining which recipients open the email. Doing this allows marketers to know who has seen the promotion or announcement that they have sent, and allows them to back-off or re-engage appropriately.

Some email web beacon tracking can be disabled by:

  • Turning off HTML display, displaying text only.
  • Turning off image display, while still using HTML.


Originally, a web beacon was a small (usually 1×1 pixel) transparent GIF or PNG image (or an image of the same color as the background) that was embedded in an HTML page, usually a page on the web or the content of an email. Modern web beacons also use the HTML IFrame, style, script, input link, embed, object, and other tags to track usage.[7] Whenever a user opens a page with a graphic browser or email reader, such image and other information is downloaded. This download requires the browser to send a request to the server storing that image or information, allowing the organization running that server to keep track of the HTML page.








Email web beacons[edit]



Tracking via web beacons can be prevented by using email clients that do not download images whose URLs are embedded in HTML emails. Many graphical email clients can be configured to avoid accessing remote images. Examples include the Gmail, Yahoo!, and SpamCop/Horde webmail clients; Mozilla Thunderbird, Opera, Pegasus Mail, IncrediMail, Apple Mail (Preferences > Viewing > Load remote content in messages), later versions of Microsoft Outlook, and KMail mail readers. Other HTML techniques (such as IFrames) can still be used to track email viewing.



A hosts file or a filtering web proxy can be used to specify that some servers are never to be contacted for any reason. This file must be continually updated to reflect the fact that new tracking servers are periodically brought online, and old ones re-purposed to serve legitimate content.

As web beacons require the email software to fetch the content, they have never been able to accurately count read rates for email campaigns. As a result of the above-mentioned measures, they may become still less effective.


See also[edit]


  6. ^ David Cancel; Felix Shnir (July 2, 2012). "Ghostery". Add-ons for Firefox. mozilla.org. Retrieved July 12, 2012. 
  7. ^ Ed Felten (May 25, 2004). "Email Tracking: It Gets Worse". Freedom to Tinker. Center for Information Technology Policy. Retrieved July 12, 2012. 

External links[edit]