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Contextual advertising uses on-site clues and additional information to place ads that are likely to be useful to site visitors, or to you.

I feel like I'm being stalked. I see the same ad all over the place. The thing is that my wife doesn't; she sees normal ads on the same pages that I see this stalker ad. What's going on?

People get pretty wrapped up when it comes to advertising, particularly anything that uses the word "tracking." They feel - as you probably do - that someone is tracking them specifically.

Well ... yes and no.

Advertisers and advertising networks use as much information as possible to provide advertisements that are relevant to you and your needs. Sometimes, that might look like they're following you around a little.

I see the most common example right here on Ask Leo! I'll use that as a place to start.

Contextual Advertising

Many web sites, including Ask Leo!, use Google AdSense to provide ads on the site, for which the site owners get paid.

Services, like AdSense, are called "contextual" advertising, because when asked to display an ad on a page, they'll look at what that page contains and then try to display ads that are relevant to the topic.

In other words, I don't choose what gets advertised - Google does.

On one hand, it's not always spot-on. On the other, Google's advertising service takes much more than just page content into account. The concept is pretty simple: provide advertisements that are as relevant to what you're doing as possible.

"The fact that thousands of people like something is useful - the fact that you do is pretty meaningless."

Of course, that means they're interested in what you're doing.

Tracking does not imply personally identifiable

We talk often about "tracking cookies", which is one of many ways that advertising services determine "what you're doing".

For example, if you run around and visit a few web hosting service web sites, as I sometimes do, you may find that advertisements on completely unrelated sites are suddenly all about web hosting.

I can see that it might feel like they're stalking you.

What's happened, however, is that the advertising service has collected information about where you've been - typically, through ads that it placed on those sites as well - and uses that to infer, "This person is looking at a lot of web hosting sites. He must be looking for web hosting. Let's show him ads for web hosting."

I run into this all the time. I regularly visit my own hosting service's site, and for quite a while afterwards, almost every site that I visit that runs Google's AdSense shows me ads for that host.

Does that imply that they know what Leo Notenboom is doing, that I specifically am being watched?

Not at all. If it did, they'd know that I'm already a customer. All that it means is that a computer algorithm somewhere simply noticed, "This browser visited these sites, so let's feed it these ads."

Advertisers and advertising networks don't care about you as an individual; what they care about and watch are the actions of millions of people in order to understand trends. They care about what the most people are looking for and acting on.

As an individual, you just aren't that interesting.

Information available to advertisers

As you can imagine, websites, advertising networks, and search engines like Google have a tremendous amount of information about what sites and topics are popular. They know how many people visit and even how long they stay. They know what words people search for and what kinds of ads that they act on.

Much of that information is made available to advertisers and some of it even to you and me.

For one example, the Google Adwords Keyword Tool and similar services show what words people are entering into search engines, how many advertisers are trying to place ads related to those words, and how many web sites provide content related to those words.

Advertisers can use this information to tailor their ads for the highest chance of success. They also use this to provide information to their advertising networks that indicate what, when, and how their ads should be displayed.

They're not saying "show Leo Notenboom these ads", but rather something more like "show these ads to browsers that have visited our website", because visiting their website could imply that the person browsing has an interest in their product.

They have no idea who Leo Notenboom is; or you, for that matter. And they don't care. What they care about is any data that implies that there might be interest in their product. They don't know who you are until you actually buy something.

Sometimes they are after you

You are just one among millions and millions of internet users. There's just no way for them to care about each and every person that might see their ads or every topic that you might discuss in an email message - that's simply too much information to process with almost no tangible benefit to them.

The fact that thousands of people like something is useful - the fact that you do is pretty meaningless. Even though the technology might use the fact that you visited a web site as one thing to factor in to what ads you might see next, you're no different than anyone else.


It could happen.

It's certainly possible that the tracking data used for advertising, or even other types of tracking information, could be used to track you as an individual.

My question to you is simply this: do you really think that you're so important or interesting that some random organization capable of this type of tracking would have some kind of interest in you personally?


If so, then nothing I've said here applies to you. Unless you take some serious and extreme steps to maintain your privacy, what you do online could be used to learn about you personally.

I just don't think that for the vast majority of us it is. If "they" are tracking you specifically, then I believe you are literally one in a million or more.

For the 999,999 of us that they really don't care about, it's not something that I worry about.

Certainly, if you've run afoul of the law in whatever country or jurisdiction might apply, then a number of doors open to law enforcement that could similarly compromise your privacy, and perhaps advertising-related information is one of them.

But for the average user, "tracking" in whatever form it might take isn't something that's worth a lot of time and effort to avoid.

Yes, sometimes they are after you.

Sometimes, the technology might even make it look like they're stalking you.

But they're not.

Most often, they're simply not wasting their time even thinking of you as an individual. You're just not that interesting.


Article C4862 - July 3, 2011 « »

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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?

July 3, 2011 7:23 PM

I've often seen this on my gmail page. I click on my OM Ships newsletter email and I get ads for boats and accessories. Then I click on an email from the Hilton hotel group and I see ads about vacations. Next I read an email from my boss about Special Prices for the month and my gmail page shows ads about discounted gear, product distribution, and canning equipment.

July 4, 2011 10:47 AM

Leo, hello,

I do like your writing!

For me, I think all the advertisements on internet, contextual or not, are very annoying because distracting from the subject you want to find.

So, I use IE7Pro trying to block the majority, though this doesn't help for 100 %. My computer still runs under XP Home, SP3, and IE8. It has the latest updates and an up-to-date Anti-Virus Avast 6.0. A few weeks ago I found out that in Avast you can easily block websites that you don't want to appear, and have entered some sites like *yieldmanager*, *googleads* and *googlesyndication*. (It is very unlikely that I would ever like to enter the related websites; and if I would, I can easily temporarily remove this words.) This really helps blocking!

I don't use any Google-software besides Gmail, Google Earth and the search engine. I have to tell that I also disabled the hourly Google-update (why should I want to be in contact with Google -especially Google!- every hour); both the updaters are now started by the Taskmanager once a week for 10 minutes.

After blocking with Avast, the Google-Earth program is moving very slowly: after starting, it will take the earth about half an hour to turn from the starting point to anywhere near my country, taking about 100 % of the CPU.

Question now is: am I really facing something like the "revenge" of Google?

No, but you are hurting the sites that you visit. For example by blocking ads on Ask Leo! (which you've done by blocking the google domains) you're affecting my ability to continue to provide this free service. The "cost" of this site is the ads that you see. If a site has too many ads, or the ads are too obnoxious, vote with your feet - don't visit the site.

July 5, 2011 11:03 AM

A large part of the panic falls upon the "media" (news, movies, tv shows) with stories about Data Mining, watchdogs keeping track of you on Facebook, etc. Supposedly there are now all the Super Databases out there that can correlate the information of millions of individuals for instant tracking on any subject. While theoretically possible today, it still requires resources far beyond a justifiable cost/benefit ratio AND the people to maintain/scan it. Even with today's supercomputers, it would still tie up hours or days of resources just to check out some random possibility of some random individual. In other words, what was once impossible is now only mostly impossible.

If that weren't so, then all arrest warrants would be served, all defaulted debts would be settled in court, and you wouldn't be seeing stories about banks foreclosing on houses where there are no mortgages.

July 5, 2011 11:29 AM

I don't like feeling stalked, even though I had already concluded that it wasn't me personally. So I just don't buy or even look hard at anything that clearly followed me. It won't stop them, but I don't agree with it, so I don't bite.

July 5, 2011 3:49 PM

I can completely sympathize with your plight, Leo. You depend on the revenue from the advertisers to bring us your excellent content without having us actually pay for it when we view it. But I wonder how many other people have become, as I have, completely immune from the ads. I simply focus on the content. I've been *trained* to focus on the content because some sites are so ad-heavy. And in all honesty, I cannot recall a time in the past, oh, 3 years when I've clicked an ad. The funny thing is that the ads that bother me the most are the ones that pop up when my mouse just goes "over" the ad. I kill those INSTANTLY. It's a conundrum for services such as yours, that's for sure!!

July 6, 2011 9:03 AM

I agree with John about the 'mouse-over' adds. If I wanted to know about 'whatever' I'd click on it. However, they are a part of what happens.

July 12, 2011 9:08 AM

Like most users I don't look at the ads. They are usually too late anyway. When I need something, I do the research, pick what I want and order it. I then start getting ads for things I no longer need ads for. Advertisers need to somehow get an ESP option to bring up ads for things I will need in the future, because ads for things I no longer need don't really do much good. Like John wrote, those mouse activated ads are the ones that get in the way and are aggravating. Those are the only ones I pay attention to, so I can remember to never buy their products. Some just start playing for no reason. I will have 6 screens open, watching some video on one and get some other voiceover going while in the middle, and I have to pause what I am watching, and search all the other windows to find the annoying ad (or ads). I have never found the ads I get to be benificial at all.

July 12, 2011 9:46 AM

Wanted to add to my last comment - since I just checked my emails and remembered how contextual ads can fail big time. I have a niece that runs marathons. She made a comment about a sports bra she just got and how well it works. Since I am a loving uncle I kiddingly made a (it was clean) comment to her about her post. Now I am getting at least two bra email ads a day. Contextual ads at their best!

Robert Marchenoir
July 22, 2011 1:24 PM

I'm sorry, but this is slightly disingenuous. Advertisers are, indeed, interested in you personally, and target you personally. This bra advert is directed to... you, personally.

They also do it to millions of others. This does not take the personal and intrusive quality out of it. What sort of solace does it give you to know you are not the only one to be personally targeted ?

July 26, 2011 5:10 PM

You can VERY easily avoid ad tracking. Go to Internet porperties and select the Privacy tab. Click on th advanced button. Check box for "Override automatic cookie handling". Set "First-party Cookies" to Prompt, set "Third-party Cookies" to Block, and finally, check the box for "Always allow session cookies".
Now, when you first go to a web site, a Cookie Requester will pop up. Here's the tricky part: before clicking on anything, read the box and "MAKE SURE THAT THE WEB SITE LISTED IN THE BOX MATCHES THE WEB SITE YOU'RE GOIN TO." IF it does, click the box for "Apply my decision to all cookies from this web site.", then click the "Allow Cookie" button.
IF it does NOT match, click the box for "Apply my decision to all cookies from this web site.", then click the "Block Cookie" button.
FYI, when you first go to a new web site, the bad cookies (The ones that track you for ads.) will always pop up first. Just block the ones that DON'T match the web site name that you're going to.
Some shopping sites do use a cookie from a transaction handler web site in order to buy from the orginal site. If you block one of these type cookies, you get a warning when you go to check out. Just go to Internet Option, Privacy tab, Sites button. Find the web site name. Highlight it by double-clicking on it and then you can change it to allow.
Most of those annoying ads will just not showup. Now if I could only find a way to kill those fly-out ads...........OH well, any company that has annoying pop-out ads will never see my money!!!!!!!

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