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Advertisers are most likely tracking you, sort of. Should you be concerned?

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This is Leo Notenboom for

This week there was news of a movement to create a "do not track" registry for the internet, much like the "do not call" registry.

Yep, big brother may not be tracking you, but it's likely that Madison Avenue is.

Most people don't realize how much their online activities are being tracked by retailers and advertisers. Most don't think about it, and those that do typically have a serious and often paranoid misconception about exactly what's happening.

For example a retail store might place your customer number in a cookie on your machine so that the next time you visit the site automatically receives that cookie and knows who you are.

Advertisers can also place so-called "third party" cookies on your machine. Since the same advertiser may be displaying ads on thousands of websites they can track where you go across those sites, even the sites you've never been to before.

So here comes the paranoia: "Oh my God, you mean advertisers are tracking ME?"

Well, yes ... but no.

They're likely not interested in you as a specific individual. There are simply too many people for them to bother tracking anyone specifically. Advertisers are interested in crowds of people, and they collect or "aggregate" the data to see what trends those crowds are following. For example, if half of the people that visit Joe's on-line book store also visit Mary's on-line grocer, that's very interesting data that might be used to tailor specific or more relevant offers to that crowd.

If you're one of the people in that crowd ... well, your identity is likely just lost in the noise. does this kind of thing within their store all the time. They track what you've purchased and even what you've just looked at, so as to make suggestions of other merchandise that might appeal to you.

Most advertiser tracking is really not much more than the same thing, only with less accuracy, applied to larger groups of people, and across a broader range of sites. Sites may not know who you are, but they may be able to better target what they offer you based on the characteristics of the kinds of crowds you appear via tracking to belong to.

Yes, you can disable cookies, but then a bunch of sites stop working completely. You can disable the third party cookies in most browsers if you like, but there are apparently ways around this that allow the same kinds of information to still be collected.

This isn't to say we shouldn't be watchful, we should. This type of tracking data could be abused. That's one reason I actually do business on-line with a handful of companies that I trust.

But in the long run, with a little bit of common sense, I'm just not that concerned.

I'd love to hear what you think. Visit and enter 11964 in the go to article number box to access the show notes, the transcript and to leave me a comment. While you're there, browse the hundreds of technical questions and answers on the site.

Till next time, I'm Leo Notenboom, for

Article C3201 - November 3, 2007 « »

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Bombay Granny
November 4, 2007 9:19 AM

While I'm not sure what you mean by 'disabling' cookies, I always go to Tools in Internet Explorer, then under Delete Browing History, I delete everything there that I can, including cookies. To date, I've haven't found doing that kept any sites from working afterward. I've also deleted cookies with AVG Anti-Spyware with no problem afterward with nonworking sites. BombayGranny

November 4, 2007 10:16 AM

Tracking is simply not an issue for many. I run Firefox with the Adblock Plus and Permit Cookies add-ons. I rarely see online ads and all cookies from most sites are immediately removed when the browser session is closed. Further, my IP address is dynamically assigned by my ISP, changing each time my DSL modem logs in, making tracking difficult by IP address.

What I'd like to know, are there any viable alternatives to push advertising?

Ken Crook
November 10, 2007 9:29 PM

Deleting all cookies deletes some that are useful, such as saved logon names so you don't have to enter them every time.

A better way is to use Karen Kenworthy's ( free Cookie Viewer. Scan the list of cookies and delete any that you don't want. Any cookies that look like tracking cookies add it to the blocked cookies list in Internet Explorer/Tools/Internet Options/Privacy/Sites. So that site can never again put a cookie on your computer.

terry coon
November 10, 2007 10:08 PM

I no longer allow CCleaner or other programs to clean out cookies. As long as everything is working OK it is just too much bother to start all over every month putting in my information in order to get another cookie. They are more useful than most users realize.

November 11, 2007 3:42 AM

I am currently not concerned with tracking, however it has been revealed that that government tracks personal phone calls and other private matters in the USA. With the co-operation of the ISPs, this can become a dangerous practice.

Chuck Newman
November 13, 2007 7:37 AM

Leo, you stated "...but there are apparently ways around this that allow the same kinds of information to still be collected." What are the techniques used? Or what do you think they are using?

Leo A. Notenboom
November 13, 2007 1:53 PM

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I've only heard it as a passing reference, but what I heard had to do with
advertiser-specific subdomains off of the parent domain. So something like would still be allowed to place and fetch cookied information
if you allow As I said, my understanding is incomplete here.


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Aaron Childs
January 30, 2008 12:11 PM

If I get a cookie while using Internet Explorer will it track the browsing that I do on my Firefox browser and vice-versa?

Leo A. Notenboom
February 2, 2008 11:41 AM

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Nope. The browsers keep separate cookie collections.


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Willa Cunningham
February 20, 2009 7:10 PM

I went into Explorer/Tools/Internet Options/Privacy/Sites and found a lot of advertisers listed in the "blocked" box, several of them are in Cookies, so that means blocking these cookies is not working! I can't get rid of ad.yieldmanager, it keeps coming back. I went in Internet Options and blocked third party cookies and with first party cookies checked the "prompt" box. Now, I am getting so many messages asking me if I want to allow a Cookie, I check the "block" option and it takes clicking on that 3 or 4 times before the message disappears....

October 27, 2009 8:51 AM

I am horrified to see that an unpublished court record of a case that was dismissed, and that I was part of years ago and withdrew from has been published for all to see when my name is searched. Most of the other claimants are not. I was not even the originator of the case. Who put this infomation under my name? Why am I being tracked? How can I have this removed? This is not done to child molesters. Can you Google their name and it says CHILD MOLESTER? I think not. Is there something I can do about this? It is as if this is something personal against me and the internet is furnishing a voice against the powerless. HELP!

November 10, 2009 12:05 AM

I believe 'trackmenot' add on doesn't work.Gzapper 1.45 may,but to get to most sites you need to 'restore the cookie'.As google wants to track you.Vidalia/tor/privoxy does work,but to write comments on Mininova,you need to restore the cookie'as they ban you 'masked' IP address.Most other IP hiders DO NOT work.'Ninjaproxy' is ok,but an ad box may keep coming up,and it leaves some history in index.dat analyzer.

November 10, 2009 12:11 AM

AnalogX Cookiewall is good,when IE or Mozilla and other cookie culling software lets some slip through,so you must delete any new entries caught within it.

November 10, 2010 5:45 AM

There is some tracking going on. A while ago I had a problem with HP printer, and I contacted support. We emailed back and forth on one email address only(aol). Low and behold they sent the customer survey to a totally different email address which had not been use. This email address is on Gmail. Another email letter I get on a regular basis has now started to send their ads to this Gmail account thought the Gmail account is very dormant. When I contacted them they just said that I could opt out. The two email address used have the same address on the pre part of the address line.

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