What is a clear GIF and how does it work?

[sunfish]

I was just reading through an online company’s privacy policy, which included the following paragraph:

If you have been offered our services through one of our marketing partners or affiliates (see “Use of Information” section below), we may share the information you enter with that partner or affiliate. To do so, we may use a technology called clear GIFs, which automatically and securely transfer the information you enter. In the future, we may also use other similar technologies on the site for the same purpose. If we do so, we will modify our privacy policy accordingly. See the “Notification of Changes” section below.

Pardon my ignorance here, but what is a clear GIF in this context? I wasn’t aware of any kind of GIF apart from the graphic file format, and I can’t see how that would apply in this case. Thanks.

[sailor]

A google search provides plenty of information.

A clear GIF [Graphics Interchange Format] or pixel tag [also known as a ‘Web beacon’] is a line of code that companies place on their websites which allows us to help them analyze their advertising campaigns and the general usage patterns of visitors to their websites.
Here’s how they work: When a user clicks on an advertiser’s Internet ad, the user is taken to the advertiser’s Web page. If the advertiser chooses to use clear GIF technology, the advertiser’s Web page will contain a clear GIF that is not visible on your screen. A GIF is a type of Web page graphic that often appears invisible because it is only 1 by 1 pixel in size. In these instances, GIFs are represented by HTML tags. HTML, or HyperText Markup Language, is the language used to create documents on the World Wide Web. The HTML tag is programmed by the advertisers to collect certain anonymous information about your visit to a particular website. This non-personally-identifiable information is sent to the DoubleClick DART ad server for processing. Companies use clear GIFs on their websites to learn more about their visitors’ use of their websites and may be used to target ads to those visitors on other websites. Depending on the type of service offering, the captured click activity may be used for reporting about the website visits or for future advertising to your browser.

Cookies and clear GIFs can also be used in emails

BTW, this is not new.

[Dan_Norder]

@sunfish

Pardon my ignorance here, but what is a clear GIF in this context? I wasn’t aware of any kind of GIF apart from the graphic file format, and I can’t see how that would apply in this case. Thanks.

Cookies are used to store information. Cookies can only be served up to a domain if you load a page or graphic on that domain. You can go to site A and they display a completely transparent GIF file served from site B, C, or D. B, C, or D can then make note of what you do on site A, as well as any other site that serves up their transparent GIFs. If enough sites serve up those invisible graphics those sites can use those cookies to make pretty good records about the types of sites you visit, for demographic purposes.

[sunfish]

I didn’t think this was new, sailor; I was just asking what it meant since I’m not exactly an HTML guru, obviously.

Thanks for the responses.

[Tower_Dweller]

Just to clarify, clear GIFs are used to track you. DoubleClick is notorious for using them, but I’d bet a lot of web-ad companies use them.

Say you’re on CNN.com. CNN.com displays an add provided by DoubleClick (for example). You’re technically on CNNs site, so it would be hard for DoubleClick to tell how many people are looking at their adds, and therefore how much to charge the advertiser. Their solution is the clear GIF. As stated before, this is usually a 1x1 image, same color as the background, so you won’t see it on your screen. What most people don’t realise is that images aren’t really bundled into the HTML of the web pages - instead the HTML just states where (on what web server) the image is located. So, it the DoubleClick add was for straightdope.com, the HTML coding for the clear GIF might look like:

<img src='http://www.doubleclick.com/clear_gif_straightdope_add.gif>

When your web browser sees this, it has to go to doubleclick.com to get the image, because it assumes you want to see it (you do want to see the pretty pictures, right?) When it does that, your computer has to tell the DoubleClick server what your web address was, so that DoubleClick knows where to send the image. Forever after that, when you browse a web site that has a DoubleClick add on it, they can match up your web address and see what kind of sites you like to look at. Look at a lot of car sites? You may notice after awhile that you’re seeing a lot of car adds.

Of course, they use cookies too, but I won’t get into that. Unless you’re really curious.