Online Ads: Why They Follow You Around the Web

Online ads permeate basically every part of the web. It makes sense from a financial standpoint why ads are used, but one question you might have is why you see an ad for something that you were reading about on a different site. You might leave Nike's website to open your email, only to see that an ad about shoes followed you in the process.

These ads are sometimes useful — like if they show up when you really would like to see them, meeting a particular need — but many online ads are revealed seemingly without your permission, crowding out content and taking up valuable real estate within your web browser. Ads are also often a big reason some web pages load slowly.

Before we can understand why certain ads are following you around on the web, it's important to understand why ads are used in the first place.

Most online ads are implemented simply to keep the lights on. In other words, if you're visiting a website that displays one or more ads, you can bet that they're generating revenue for that website, which in turn pays for things like web hosting, compensation for the writers and developers, etc.

Even though these ads are helping to make it possible for the sites you visit to stay in business, that's not to say that ads are welcome. A wide variety of studies show that people find online ads intrusive, annoying, and would rather turn them off all together. It's clear that most people using the web don't appreciate ads in their websites, blogs, video sites, or social networks. These unsolicited, even somewhat aggressive (and occasionally offensive) ads are unwanted interruptions.

However, as people have grown used to ads online, advertisers have become increasingly more creative with their marketing tactics, creating something called "behavioral retargeting."

Behavioral retargeting, or ad remarketing, is basically a reminder: if the person didn't buy something the first time around, the ad follows them and offers another opportunity to complete the purchase.

The basic idea is that the ad targets individuals that already showed an interest in the product. Instead of blasting a particular ad to people who may not have any interest in buying the product, ad retargeting latches on to the people that do show interest, and shows them an ad in hopes that they'll come back to buy the item in question.

You can see how this could be very helpful for both you and the company serving the ad. You get reminded about things you're interested in, even across your devices (e.g., you can search for TVs on your computer and see a flat screen TV ad on your phone sometime later), while the company gets another shot at having you complete the purchase.

Plus, a company using behavioral retargeting techniques has an advantage over the companies that don't. If while searching for TVs, you land on a dozen websites but still haven't figured out what you want, the brand using ad remarketing might show you their TV once more later in the day long after you've stopped looking. Now that you've seen this particular TV more than once, it might reinforce your attachment to it. The ad might even give you a coupon code to use with the purchase.

However, to some, personalized ads are just creepy. If you don't like the personalization and you aren't a fan of uninvited habit trackers, it can feel like an invasion of privacy.

Here's a scenario: you just searched for something on Google, took a few minutes to sift through the results, and then decided to visit Facebook. Lo and behold, within just a few seconds, what you just searched for on Google is now displaying as an ad on your Facebook feed!

How is this possible — is someone following you, logging your searches, and then retargeting you on a completely different website? 

To put it simply, yes. Here's a brief overview of how this works:

1. You visit a website to purchase a pair of gloves. The ones you've chosen are a good price, but you think you might be able to get a better deal somewhere else. 
2. You leave the gloves in the shopping cart, and visit another site. 
3. As soon as you arrive on the site's home page, an ad — featuring the gloves you just looked at — shows up on the side of the page.
4. You've just been retargeted!

Behavioral retargeting is a very clever process by which advertisers keep track of their customers' browsing habits, and then use these to lure users back to their sites after they've left.

How does this work? Basically, the website implements a bit of code within their site, which in turn gives a tracking code to new and returning visitors. This small piece of tracking code — called a cookie — gives the website the ability to track users' browsing habits, figure out what they're looking at, and then follow them to another site, where the ad showing what you just looked at will show up.

The ad not only displays what you were just looking at, but it could also offer a discount. Once you select the ad, you're instantly returned to the site where you can buy your item (possibly at a lower price). 

Sure, it's nice to get a bargain on something you were going to buy anyway, but not everyone appreciates being followed around the web by ads, even if the ads have zero insight into your personal identity (and they don't).

It's one thing to see ads for something on sites you don't have any personal information on, but what about sites like Facebook, LinkedIn, or even Google, where users have given out phone numbers, personal addresses, and other information that could be harmful in the wrong hands? 

If you're concerned about privacy online, and would like to stop websites from being able to retarget you, there are a couple of simple ways to accomplish this. 

• Get an ad blocker: You can prevent ads from even showing up on the websites you visit by using an ad blocker; simple software applications that block websites from sending ads to you. Every web browser has an ad block extension available, one of the best being AdBlock Plus. 
• Go incognito: Most browsers have an incognito, or private browsing mode that you can go into to prevent cookies from being stored while you use the web.
• Turn off cookies: You can set your web browser to not accept cookies to prevent retargeting techniques from storing cookies, and thus stop the ad from following you. All major web browsers have this option available in the settings, but remember that disabling cookies means that even legitimate cookies (like what's used to keep you logged in to your email and social media accounts) will not be saved either, preventing you from staying signed on to those sites. An alternative is to manually delete the browser cookies every few days.
• Opt out of ads on Google: If you use Google, you have some control over muting ads, which will affect personalized ads you see when signed in to your Google account. Opt out from your Ad Settings page. Note that this works across all devices that are signed into the Google account you're turning this off for, but it will only disable personalized ads in specific scenarios. 

Pop-up ads could be related to ad remarketing, but they could also be entirely different, and a symptom of a computer issue.

If you've ever had weird pop-up windows that just won't go away, hijacked browser settings, internet preferences inexplicably changed, or a very slow web search experience, then you've most likely been the victim of spyware, adware, or malware.

All three of these terms mean pretty much the same thing: a program that monitors your actions, generates unwanted ads, and is installed on your computer without your explicit permission or knowledge.

Beyond targeted and/or personalized ads like we've talked about above, if you're consistently seeing annoying pop-up ads (smaller browser windows that "pop up" in the middle of your screen) or even more annoying, browser redirects (you visit a site, but your browser is instantly directed to another site without your permission), then you most likely have bigger problems than simple ad personalization. Most likely, the issue is a virus or malware on your system, and your computer is infected. 

Most often, these malicious programs are installed within another program. For example, say you downloaded a seemingly innocent PDF editing program, and unbeknownst to you, annoying adware was bundled within it. You'll know you've been infected if you start seeing random ad banners, URLs appearing where they shouldn't be, pop-up ads full of false advertising, or other undesirable side effects. 

If you're not careful, spyware, adware, and malware can take over your system, causing it to slow down and even crash. These annoying programs are not only irritating, but they can also cause real problems for your computer.