For Mauricio Freitas, publisher of the New Zealand Geekzone website for mobile enthusiasts, ad blocking software has been a major headache. Last year his site lost more than one quarter of its display ad impressions because of visitors running these increasingly popular — and free — browser add-ons that filter out advertising before users ever see it. "We serve about two million page views a month. The impact on our revenues has been significant," he says.
Viewing ads is part of the deal if users want content to be free, says Freitas. The use of ad blocking software breaks that implicit contract. What's more, he continues, the vast majority of visitors who use ad blockers aren't interested in making even a small payment in exchange for an ad-free site. Only 1,000 of Geekzone's 350,000 unique monthly visitors have been willing to pay $25 a year for an ad-free option, even when Freitas has thrown in other perks.
And some believe that today's ads aren't as obnoxious as yesterday's. "We all hate the dancing monkey and display ads that blink at us," says Mike Zaneis, senior vice president at the Interactive Advertising Bureau (IAB), a trade group that represents publishers and ad sellers. "Do you see larger ads, or sponsored ads today that take over the entire page for three seconds? Absolutely. But they're not the spammy, irrelevant messages that most of us think of from five years ago." The problem for publishers, he says, is that most ad blockers don't just block annoying or intrusive ads — they block everything.
How ad-blockers work
Ad blockers are content filters that rely on predefined filter lists to identify and remove ads. They work by compiling lists of expressions associated with ads and using pattern matching to compare those against outgoing requests made by the user's browser.
Ad blockers may also block tracking scripts, which in turn prevent third-party ad networks from delivering ads to a user's browser by way of the publisher's site. "Before the page is rendered, Adblock Plus modifies it, strips off the request to the ad service or tracking scripts and injects CSS to repair the site so it doesn't look broken," says Till Faida, president of Adblock Plus.
Think of it as surgically removing the ads and then closing up the holes. To the user there's no evidence an ad ever existed.
Because they interrupt communications with third-party ad networks, dedicated tracking blockers such as Disconnect also block ads from those sources. Disconnect does so by examining the host name for any outgoing browser request and blocking requests to hosts associated with ad networks that track users' activity across the Web. But the intent is to block tracking, not ads, says co-CEO Casey Oppenheim, and these tools still let through "first-party" ads produced by the publisher.
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