Many websites rely on advertising for revenue. Google knows this, even offering its own advertisement placement service, AdWords. However, not all types of ad placements are regarded equally.
Google considers some advertising tactics disreputable or spammy and will penalize sites that employ them. It's important to know which types of advertising are acceptable, and which ones have the potential to get you in trouble.
1. Excessive ads above the fold
"Above the fold" refers to what a viewer can see when a page is first loaded. A viewer typically visits a webpage for the content, and they expect content to be the first thing they see. If there is nothing but advertisements above the fold, with the actual content buried somewhere below it, then the page is not well designed.
Google takes this into account when determining rankings -- pages with an excessive number of advertisements above the fold are penalized. One banner ad is acceptable, of course.
2. Full-screen floating ads
Full-screen floating ads, also known as overlay ads, are those that fill visitors’ entire browser windows, preventing them from viewing any content on the website until the ad finishes or they locate the button to close it. Because they block the visitor from seeing any of the content on the page, impatient people who don't want to hunt for the tiny "X" to close the ad are more likely to just hit the back button.
This contributes to a site's bounce rate -- the number of visitors who, upon coming to the page, immediately leave it. Google considers a high bounce rate to be a sign of a poor site, and as such, will give it a lower ranking.
Roadblocks, also called interstitials, are forms of full-page advertising that go beyond full-screen floating ads. They redirect visitors to a full-page ad at a different URL, along with a button for the user to continue to their destination. Roadblocks are even more likely to contribute to a high bounce rate than full-screen floating ads. Upon seeing that they're getting redirected to a different URL, most visitors' instinctive reaction is to assume they clicked on spam and immediately hit the back button.
Users may do this before the page even finishes loading and without looking for the “continue” button. As with full-screen floating ads, putting up obstacles between visitors and the content they seek is only likely to result in penalization.
4. Auto-playing audio or video ads
There are few things as disruptive to user experience as auto-playing ads with audio. Faced with the sudden burst of noise, most visitors are going to frantically try to pause or mute the ad. If they can't find the stop button quickly -- or worse, if there is no way to mute the sound -- they'll close the window. Even more detrimental are multiple auto-playing ads, which result in overlapping audio and incoherent babble.
The worst-case scenario involves a visitor in a public place such as a library where the sudden sound causes a disruption or draws attention. The website visitor, the person you are most trying to please with your website, will feel angry and embarrassed. These emotions are not likely to result in repeat visits from those users, let alone result in a purchase.
If you feature audio or video ads on your site, make sure they only play when clicked. Triggering video or audio on a mouse rollover isn't enough -- that just turns large sections of your website into audio landmines, which the typical visitor would rather avoid than navigate.
5. Ads disguised as content
To get more traffic to pay-per-click ads, some sites attempt to disguise the ads as content. Common techniques include a "related content" section at the bottom of an article, which looks like a series of links to articles on similar topics, or a navigation toolbar that doesn’t actually take you anywhere worthwhile.
These links are actually all ads. Any method that seeks to deceive users into clicking on advertisements is against Google guidelines, and can result in a site being penalized.
6. Multiple ads dividing main content
Some sites try to maximize the impact of their ads by placing them near the main content rather than off to the side or bottom. In the case of multiple advertisements, this results in an interspersed pattern of content: ad, content, ad, content, ad, and so forth.
Google's quality guidelines specifically call this out as poor site design as it is jarring to the visitor and disrupts the flow of the content. If you want to place an ad within your content, it might be best to limit it to only one per page.
7. Excessive pagination
Having realized that there are only so many ads that can be crammed onto a page without squeezing out the content, some website designers came up with an ingenious solution: split the content into chunks and spread it out across multiple pages, each of which can have its own advertisements. This technique results in an article that is delivered in miniscule chunks, which are easily lost among the sea of advertisements.
In addition to being extremely frustrating to visitors, this type of structure also runs afoul of Google's content guidelines. Instead of seeing one page with a richly detailed article, Google will see 30 pages with barely any content and consider none of them worthy of a high search-result ranking. If you're going to employ pagination, keep it to two or three pages at the most and make sure each page contains enough content on its own to be considered informative and high quality by Google.
Keep Google, and users, happy
What types of advertisements you run on your site and where you place them can greatly affect how your site ranks in Google's search results. Large amounts of advertisements placed above the fold or multiple advertisements that break up the main content of a page are prohibited and can result in a Google penalty. Intrusive advertisements, such as those that block users’ ability to see the content or those that feature auto-playing audio, will result a poor user experience and be reflected by a lower ranking.
There's nothing wrong with relying on advertising for revenue. But to avoid any surprise penalties, keep in mind Google's quality guidelines and the possible impact your ad placement can have on user experience.