Pop-Up Blocker

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What Does Pop-Up Blocker Mean?

A pop-up blocker is software that prevents pop-up windows from appearing on a website. Some pop-up blockers work by immediately closing the pop-up window, while others disable the command that calls the pop-up window. Most browser software allows the user to turn the blocker on or off.


Pop-ups are usually used by advertisers as a way to deliver ads, but they distract Web users from their experience and most consider them a nuisance. This is why pop-up blockers were developed and have become a part of most Web browsers.

Including a pop-up blocker in browser software helps it to work more effectively, because the browser knows when a website is attempting to open a new pop-up window and just ignores that request. A pop-up blocker is also known as a pop-up killer.

Techopedia Explains Pop-Up Blocker

Pop-ups are frequently used by websites to advertise products or features. They are therefore meant to be as eye-catching as possible. This is achieved by making the pop-up open in a small secondary window, which becomes the active window.

To get the maximum amount of attention, a pop-up may also feature bright colors, animation and motion. For browsers that support tabbed browsing, the pop-up may open in a secondary tab instead of a whole new window. Pop-ups are commonly generated using JavaScript.

For many users, pop-up behavior is quite irritating. Users may feel ambushed and distracted by pop-ups, which almost always consist of advertisements unrelated to the Web content the user is currently viewing.

In the late ’90s, browser manufacturers answered consumers’ desire to inhibit pop-ups by releasing new versions of Web browsers with the ability to block them. The Opera browser was the first to offer this feature.

Pop-up blocking is usually enabled by means of a check-box that one must tick to enable pop-up blocking, or untick to disable. All the major browsers now support pop-up blocking.

Pop-up blockers may also be installed as third-party software tools. These typically incorporate additional features such as ad blocking and highly customizable pop-up blocking options. Some of the best VPNs also include ad and pop-up blockers along with other security tools. For the majority of users, however, the blockers built into all major browsers are perfectly adequate.

Not all pop-ups are a nuisance. In fact, some are very helpful. For example, pop-ups are often used to provide guidance to users on how to fill in a form on a Web page. Unfortunately, modern browsers may accidentally block these as well (hence the ability to enable or disable the whole feature).

Some browsers have the ability to discern which pop-ups are genuine tools on the website and treat them differently from pop-up advertisements, a feature called intelligent blocking. Some browsers indicate to the user when they have blocked a pop-up, usually by means of a small information bar lasting a few seconds, an audible signal, or both.

Website designers and owners, in turn, have found creative new ways to circumvent pop-up blockers. A variant of the pop-up is the pop-under; just like a pop-up it also creates a secondary window. The difference is that the pop-up window does not become the active window. Instead, it hides behind the main browser window until it’s closed, whereupon the user can view the pop-up.

Other sites use a so-called hover ad, which is also a superimposed advertisement. However, a hover ad is created using DHTML so that the browser does not recognize it as a secondary window and close it.

Although such advertising methods are crafty, they may backfire on the website’s owner if users simply stop visiting the site because of the in-your-face, distracting nature of pop-ups, pop-unders and hover ads.


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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.