How Web Advertising Works

Black Friday super sale promotional web advertising
Some web advertising is obvious but others like native ads can be harder to detect. Alem Omerovic / Getty Images

You have probably noticed that across the Web, two different things are happening right now:

  1. More and more sites are asking you to pay a fee to subscribe to all or part of the Web site.
  2. Advertising is becoming more and more "in your face." There are now pop-up ads, ads that play music and sound tracks, ads that swim across the screen, and so on.

The second trend is true of nearly all commercial Web sites. There are many new forms of Web advertising, and they are more and more obvious. Many Web users have questions about all of these new ad types. For example:


  • Why do Web sites have so many ads now?
  • Why do Web sites allow pop-up ads that open new windows? (Many people hate closing them all.)
  • Why do Web sites allow these floating ads that cover the content so I cannot read it?
  • How can I make all these ads go away?

­In this article, we will look at all the different forms of Web advertising in use today, as well as the economics that are driving them, so that you can have a much better understanding of how Web advertising works. Whether you are a casual surfer or someone running your own Web site, you will find this article to be a real eye-opener.

In the Beginning: Banner Ads

­ When th­e Web first started being a "commercial endeavor" around 1997 or so, thousands of new sites were born and billions of dollars in venture capital flowed into them. The sites divided into two broad categories:

  • E-commerce sites - E-commerce sites sell things. E-commerce sites make their money from the products they sell, just like a brick-and-mortar store does.
  • Content sites - Content sites create or collect content (words, pictures, video, etc.) for readers to look at. Content Web sites make their money primarily from advertising, like TV stations, radio stations and newspapers.

­In the beginning, "advertising" on the Internet meant "banner ads" -- the 728x90-pixel ads you see at the top of almost all Web pages today (including this one). In 1998 or so, banner advertising was a lucrative business. Popular sites like Yahoo could charge $30, $50, even $100 per thousand impressions to run banner ads on their pages. These advertising rates provided fuel for much of the venture capital boom on the Web. The idea was that sites could start up and increase their page impressions to make easy money from banner ads. If a site could generate 100 million page impressions per month, it could make $3 million per month with banner ad rates at $30 per thousand impressions.


Where did numbers like $30 or $50 per thousand impressions come from? That's what magazines typically charge for full-page color ads. The Internet took the same payment model and applied it to banner ads.

At some point, advertisers came to the conclusion that banner ads were not as effective as full-page magazine ads or 30-second TV commercials. At the same time, there was an incredible glut of advertising space -- thousands of sites had a million or more page impressions available per month, and companies like DoubleClick began collecting these sites into massive pools of banner-ad inventory. The economic principle of "supply and demand" works the same way on the Web as it does everywhere else, so the rates paid for banner advertising began to plummet.

Let's look more closely at what determines banner ad rates.


Banner Ad Prices

A company buys advertising for one of two reasons:

  • Branding
  • Direct sales

­Branding refers to the process of impressing a company name or a product name onto society's collective brain. Let's say you have come up with a new brand of soda, or you are openi­ng a new restaurant, or you are selling a new widget. You want to get the product's name (and sometimes the product's features and benefits) firmly planted in people's heads. This is branding.


Branding happens with both new and existing products. When you see a billboard that says nothing but "Coke" on it, or you see a NASCAR car that says "Tide" on the hood, or you see a feel-good ad on TV about a car company or an oil company but there's no mention of a product, that is branding. The advertiser does not necessarily expect you to do anything today -- the advertiser simply wants to impress itself on your consciousness.

On the other hand, a direct sales ad is an ad that is trying to get you to do something today, right now, as you look at the ad. The advertiser wants you to:

  • Click on the ad
  • Call an 800 number
  • Drive immediately to the store

...or do some other active thing so that you buy something, download something or sign up for something today. The advertiser counts the direct responses to the ad and measures the effectiveness of the ad by those responses.

What branding advertisers came to feel about banner ads is that banner ads are not the most effective vehicle for branding. Relative to a magazine ad or a TV ad, banner ads are small and easily ignored.

What direct sales advertisers came to feel about banner ads is that the response rate for banner ads is low. For most banner ads, the industry average seems to hover between two and five clicks per 1,000 impressions of the ad. That is, if a banner ad appears on 1,000 Web pages, between two and five people will click on the ad to learn more.

Those five clicks per thousand impressions don't have much value to most advertisers. The reason is because those five clicks will not all generate sales. Out of 100 clicks, perhaps one person will actually do the desired thing (buy something, download something, etc.).

An Example

Here's an example. Let's say that a publisher wants people to buy a book, and hopes to increase sales of the book through advertising. The publisher has budgeted $3.00 per copy of the book to spend on advertising. If the publisher is paying $30 per 1,000 impressions for banner ads and purchases 100,000 impressions for $3,000, here is what happens:

  • The banner ad appears 100,000 times.
  • Let's say the response rate is five clicks per 1,000 impressions, so 500 people click on the ad during the time the 100,000 total impressions are running.
  • If two percent of those 500 people actually purchase the book, that results in 10 purchases.
  • The publisher had to pay ($3,000/10) $300 for each book purchased through that ad.

­Obviously, paying $300 to sell one book is not a good economic model for a publisher, especially since the budget is $3.00 per book. For this type of advertising to work for the publisher, the publisher would need to pay 30 cents per 1,000 impressions, rather than 30 dollars.

The Result

So banner ad rates began to decline. Today, if you shop around, you can buy banner ads from thousands of Web sites or brokers for 50 cents or so per thousand impressions -- which is pretty much exactly what they are worth to a person who is trying to sell something with banner ads using a direct sales model.

It is possible for some Web sites to charge more than 50 cents per 1,000 impressions. For example, the top 100 or so Web sites can charge a premium because of their size. There is also a process called targeting. For example, if you want to sell a GPS, you can advertise on the HowStuffWorks GPS article and get a targeted audience for your ad, which will typically increase the click-through and response rate for the ad. Yahoo and many search engines target their banner ads to the search words people type in, and they charge more for these targeted ads. But for most other Web sites, there is very little money to be made from banner ads.

In order to charge more than 50 cents per thousand impressions, Web sites have to offer ads that either:

  • Have a lot more branding power
  • Get a much higher click-through rate

Therefore, you find many different advertising formats and experiments on the Web today.

Sidebar Ads

­­ A sidebar ad (also known as a skyscraper ad) is similar to a banner ad, but it is ­vertically oriented rather than horizontally. Because it is vertical, the height of a sidebar ad can often reach 600 pixels or more, and sidebars are generally 120 pixels wide.

A sidebar ad has more impact than a banner ad for at least two reasons:


  • A tall sidebar ad is two to three times larger than a banner ad.
  • You cannot scroll a sidebar ad off the screen like you can a banner ad. With a banner ad, you can scroll just 60 pixels down and the ad is gone. With a sidebar ad, the ad is with you much longer.

­Because of this increased impact, sidebar ads have higher branding power and a higher click-through rate. A typical sidebar ad has a click-through rate of 1 percent (10 clicks per 1,000 impressions), or about two to three times that of a banner ad. Advertisers will typically pay $1.00 to $1.50 per 1,000 run-of-site impressions for sidebar ad placement. Advertisers pay more for targeted sidebar ads, just like they do with targeted banner ads.

Varied Shapes and Sizes

The orange ad in the upper right is 250x250 pixels. Ads this size or larger can be found within the text of articles in some cases. They act like magazine ads that break up the text to get more attention.

­ Banner­ ads and sidebar ads have standard sizes, but in the last year or two people have tried all different sizes and placements. Here are three examples:

On this page you can see a narrow strip for Netscape at the top, a standard banner ad, a square AOL ad mid-page, and four smaller ads along the bottom.
On this page there is a round WSJ button up top along with ads for Casio, Ubid and Radio Shack along the side. At the bottom there are tiny ads for four money sites along with small ads for and (even the advertising is sponsored!).

Sites don't get paid much for these smaller ads, because generally the click-through rates are low. But by putting 10 ads on the page, it can add up to $2 per 1,000 page impressions.


Pop-Up and Pop-Under

A typical pop-up ad

­ A pop-up ad is ­an ad that "pops up" in its own window when you go to a page. It obscures the Web page that you are trying to read, so you have to close the window or move it out of the way. Pop-under ads are similar, but place themselves under the content you are trying to read and are therefore less intrusive.

A typical site with two pop-up ads that appear on top of the home page

Pop-up and pop-under ads annoy many users because they clutter up the desktop and take time to close. However, they are much more effective than banner ads. Whereas a banner ad might get two to five clicks per 1,000 impressions, a pop-up ad might average 30 clicks. Therefore, advertisers are willing to pay more for pop-up and pop-under ads. Typically, a pop-up ad will pay the Web site four to 10 times more than a banner ad. That is why you see so many pop-up ads on the Web today.


Floating Ads

A screenshot of a typical floating ad for a Norton product: This ad is completely animated, with four or five moving parts. The ad plays for about 15 seconds. Note that it does have a "Close" button, so there is a way out of this ad. Many floating ads do not have this feature.

If you h­ave ever been to a Web site that uses them, you know what "floating ads" are. These are ads that appear when you first go to a Web page, and they "float" or "fly" over the page for anywhere from five to 30 seconds. While they are on the screen, they obscure your view of the page you are trying to read, and they often block mouse input as well.

This page has been set up so that a floating ad should appear every time you load the page. If you have the right browser combination, then you should have seen the ad when you clicked into this page. The ad is about 5 seconds long. It floats over the page and then should settle in the upper right hand corner. If you would like to see lots of other examples of different floating ad campaigns, see and


Floating ads are appearing more and more frequently for several reasons:

  • They definitely get the viewer's attention. They are animated. Many now have sound. Like TV ads, they "interrupt the program" and force you to watch them. They can take up the entire screen. Therefore:
  • From a branding standpoint, they are much more powerful than something like a banner ad or a sidebar ad. They cannot be ignored.
  • They have a high click-through rate, averaging about 3 percent (meaning that 30 people will click through for every 1,000 impressions of a floating ad).

­ The high click-through rate, as well as the greater branding power, means that advertisers will pay a lot more for a floating ad -- anywhere from $3 to $30 per 1,000 impressions depending on the advertiser and the ad. Because they can pay a lot of money, Web sites are willing to run floating ads.

The only problem with floating ads is that they annoy people. Some people become infuriated by them, and will send death threats and three-page-long rants via e-mail. That is why you do not yet see them everywhere.

The annoyance problem points out something interesting about advertising, however. When pop-up ads first appeared, they bothered lots of people and you did not see them on very many sites. After a while, people got used to them and stopped complaining, and now pop-up ads can be found on tons of sites.

Television provides another useful example. If television programs were ad-free today, and suddenly a TV station were to start running eight minutes of advertising every half hour right in the middle of programs, people would go NUTS! There would, quite possibly, be riots in the streets. But since we are all familiar with TV ads, they don't bother us much. In fact, during the Super Bowl, the ads are a big part of the show!

As people get used to floating ads, they will become more common.

Unicast Ads

­ Unicast ads are a wh­ole different animal, and they are spreading across the Web as a way to get serious ad clicks. A Unicast ad is basically a TV commercial that runs in a pop-up window. It is animated and it has sound. The ads can last anywhere from 10 to 30 seconds.

If you would like to see examples of ads from Unicast, go to


A Unicast ad has roughly the same branding power as a TV commercial. However, a Unicast ad offers something that TV ads cannot -- the ability to click on the ad for more information. And people do click on them at an amazing rate -- a 5-percent click-through rate (50 clicks per 1,000 impressions of the ad) is not uncommon.

Because Unicast ads have branding power and because people click on them, $30 per 1,000 impressions is a common rate paid to Web sites. Because they pay so well, they are likely to spread rapidly.

Other Variations

A small video ad appears in the right sidebar on this CNN page, with sound, and plays for 30 seconds. The reader can control the ad with the three buttons (Play, Pause, Stop) underneath the ad.

­ You are likely to see many other variations on the theme as time goes on. Here are seve­ral examples:

  • HowStuffWorks offered something called a "takeover campaign" a while back. Viewers visiting HowStuffWorks saw a large ad when they first came to HowStuffWorks each day, and then they saw the message reiterated throughout the site in banner and sidebar ads. The advertiser essentially "took over" the site for one or more days. The approach worked very well as a branding play because the brand was visible to viewers throughout their entire visit to the site. Click-through rates were very high. Advertisers were pleased with the results, and negative reader reaction was minimal because everyone was familiar with banner and sidebar advertising.
  • CNN has experimented with streaming sidebar ads, as shown here:
  • Pull-down banner ads have appeared on some sites. Their operation varies depending on the site. On some, when you mouse over the banner ad, it expands to fill much of the page. On others, the banner ad is expanded-size initially, then shrinks to normal size after several seconds. Here's an example of one that shrinks after several seconds: When you first enter the page, the banner ad is large... ...and then shrinks to a normal size (note that this site is using oversized banners at 725x70 pixels, and the width of the site is built around its banner ads). Buttons on the ad let you re-expand it if you choose to.



­All of these different ad formats are trying to find combinations that give advertisers what they want -- high click-through rates and branding power. In return, advertisers are willing to pay Web sites for running these ads because the ads work.

Multiple Web Ads: How Bad it Can Get

­ This page could ­be set up to give you a barrage of advertising:

  • There are multiple banner and sidebar ads.
  • Imagine that there are two or three pop-under ads.
  • Imagine that there is a floating ad.

If there were a Unicast ad playing over the top of it all, that would be a worst-case scenario. It is hard to imagine a Web page having much more advertising than this.


I have never seen a Web site go this far, but some get close. The reason you see things like this is because it pays well. A Web site can, in theory, make between $40 and $50 per 1,000 impressions if every page were loaded with this much advertising. That is a lot of money. On the other hand, this much advertising tends to turn readers off.

An Example

So why do Web sites end up running so many ads like this?

Let's create a hypothetical Web company and use it as an example. The company is called XYZ, and it is a small, successful content site. Here are some of its parameters:

  • The company has 1,000,000 visitors a month who read, on average, eight pages per visit. So there are 8,000,000 page impressions per month.
  • The company has 10 employees, with an average pay of $40,000 per year. Some make more, some make less, and $40,000 is about the middle. That means payroll is about $36,000 per month (when you add in the 8% employer match for Social Security and medical).
  • Benefits per employee run $400 per month, or $4,000 total per month.
  • Office rent is $4,000 per month.
  • Equipment leasing and bandwidth to run the Web site is $4,000 per month.
  • Other costs include phone lines, power, office furniture and computers, legal/accounting fees, travel, advertising, coffee, subscriptions, blah, blah, blah. Let's say it averages $20,000 per month in "other costs."

XYZ therefore spends $68,000 per month.

If XYZ places banner ads on its 8,000,000 pages per month and gets 50 cents per thousand impressions, it makes $4,000 per month. Obviously, that isn't going to cut it -- $4,000 per month does not even cover one person, or the bandwidth and equipment.

If XYZ is able to sell floating ads or Unicast ads at $30 per 1,000 visitors (not page impressions -- visitors), then the site's 1,000,000 visitors per month can generate $30,000 per month. That, plus the banner ads, gets the company to $34,000 per month. You can see that there is still a problem -- XYZ is only halfway to breaking even. But $34,000 is much better than the $4,000 that banner ads alone would generate.

Keep in mind that there is no guarantee that XYZ will be able to sell all of its ad inventory. It would take a very good sales person (or sales force) to find companies to sign contracts and pay for all of that inventory (8,000,000 banner ad impressions per month, 1,000,000 Unicast impressions per month). There is no guarantee, for example, that XYZ can find companies to pay $30 per 1,000 impressions for 1,000,000 floating ads or Unicast ads. If XYZ is able to sell ALL of its inventory, it is extremely lucky, so getting to $34,000 per month every month is a long shot.

XYZ therefore needs to find other ways to make money. If XYZ now:

  • adds in sidebar ads
  • adds in 250x250 ads in the middle of articles
  • adds in pop-under ads
  • adds in one or two other ad features

...then the company might be able to bring in another $15,000 per month, and it is getting close to its goal of breaking even.

That kind of math is exactly why you see so many ads on Web sites today. It's either:

  • Lots of ads
  • Switch over to subscriptions (and hope that you can get 50,000 people to subscribe -- no easy task)
  • Go out of business

A Web site is a business, and it must cover its expenses to survive.

For more information on Web advertising and related topics, check out the links on the next page.

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