A popover is an overlay which covers the material in a web browser without the need to create a new window. Popovers are also known as overlays. This programming trick is most commonly used for Internet advertising, although there are some other uses for popovers. One of the issues with the popover ad from the point of view of web users is that these ads usually cannot be blocked by ad blocking software, which means that the user is forced to see them. This is, of course, exactly why Internet advertisers like popovers.
The popover ad probably would not have been developed if people had not figured out how to block popup ads. Popup ads are ads which open in a new browser window, and they operate with a script, which means that software can be built to stop the script before it starts. In response to a lack of advertising exposure thanks to web users who used popup blockers and ad blocking software, the popover was devised.
In a classic example of a popover, a web user navigates to a page and an ad materializes over the material on the page. Sometimes the ad covers the whole page, and sometimes it only appears in one section. In either case, the ad may be closable with a button, or it may remain on the page until the user navigates away, or until the ad closes itself.
Self-closing popover ads are often used to play animated advertisements, forcing the user to sit through the ad before he or she can view the material on the page. Popover ads may also scroll across the page, allowing the user to navigate the page in a truncated fashion until he or she clicks the ad. Sometimes, the information on the popover ad is misleading; for example, a button marked “close” might actually open an ad in a new window.
One of the non-advertising uses of popovers is in sites which require paid subscriptions. In these cases, users can navigate to a page and get a glimpse of the content, but a popover hovers over the content, informing the user that he or she will need to pay for access. This tool can be used to attract search traffic, getting eyeballs on the page in the hopes that people will subscribe to the site. It also circumvents the “subscription only” tags which some search engines use to identify sites in a list of search results, since it allows users to land on a real page rather than a subscription paygate.