Pop-up ads or popups are a form of online advertising on the World Wide Web intended to increase web traffic or capture email addresses. It works when certain web sites open a new web browser window to display advertisements. The pop-up window containing an advertisement is usually generated by JavaScript, but can be generated by other means as well.
A variation on the pop-up window is the pop-under advertisement, which opens a new browser window hidden under the active window. Pop-unders do not interrupt the user immediately and are not seen until the covering window is closed, making it more difficult to determine which web site opened them. Pop-unders can be extremely annoying for people who are used to leaving several tabs prepared for another session, as unnoticed pop-unders will be considered by the browser as the last open window. This will cause the browser to open the ad at the next start, instead of the prepared tabs.
Pop-up blocking
Opera was the first major browser to incorporate tools to block pop-up ads; the Mozilla browser later improved on this by blocking only pop-ups generated as the page loads. In the early 2000s, all major web browsers except Internet Explorer allowed the user to block unwanted pop-ups almost completely. In 2004, Microsoft released Windows XP SP2, which added pop-up blocking to Internet Explorer.
Most modern browsers come with pop-up blocking tools; third-party tools tend to include other features such as ad filtering.
Blocking of legitimate "pop-ups"
In some cases a pop-up is desirable and problems can arise when they are inappropriately blocked.
- Many websites use pop-ups to display information without disrupting the page currently open. For example, if you were to fill in a form on a web page and needed extra guidance, a pop-up would give you extra information without losing any information already entered into the form. Most pop-up blockers will allow this kind of pop-up, however, some will reload the page, losing any information that was entered.
- Some web based installers such as that used by McAfee use a pop-up to install software.
- On many internet browsers, holding down the ctrl key while clicking a link will allow it to bypass the popup filter.
Circumventing pop-up blockers
Advertisers continually seek ways to circumvent such restrictions. For example, some pop-up ads are generated using Adobe Flash. Since pop-up blockers only blocked the JavaScript method, the Flash method would bypass the pop-up blocker.
A combination of a banner ad and a popup window is the "hover ad", which uses DHTML to appear in front of the browser screen. With the use of JavaScript, an advertisement can be superimposed over a webpage in a transparent layer. This advertisement can appear as almost anything the author of the advertisement wants. For example, an advertisement can contain a Adobe Flash animation linking to the advertiser's site. An advertisement can also look like a regular window. Because the advertisement is a part of the web page, it can be blocked with third-party ad blockers such as Adblock or by using custom style sheets. DHTML ads can be very CPU intensive, sometimes bogging down older computers to the point of unusability.
Pop-up generators
A popup generator is a computer application used to design, produce, store, install and maintain popup advertisements. Popup generators vary from simple ones that generate blockable old-style annoying popups, to complex and sophisticated computer software applications, used to develop feature rich popup ads and hover ad windows.
