For dotcom sites eager to ensure an advertiser's message gets noticed, the pop-up window is a valuable tool. The “pop-up” puts the advert in the visitor's face by overlapping in on top of whatever they are viewing. This draws the eye and ensures its presence cannot be ignored.
As a pop-up leaves the main browser window intact, they have applications beyond displaying adverts. Imagine a situation where you want to explain to the customer what an excess is after you've provided a quotation. You may have a link marked “What is an excess?” on your page. Clicking on it produces a small window that sits over the page. In the window is the explanation and a button marked “Close this window”. When that button is clicked, the window vanishes, leaving the visitor free to continue with the quote. This is easier than putting the information on the quotation page, or having the user going through different pages, each one taking time to download.
However, pop-ups are not without their share of problems. They take the “focus” off the browser, effectively taking control of it. Any keystrokes the visitor makes are sent to the pop-up for processing. The result is nothing happens, which confuses the visitor. This is not what you want associated with your business.
This kind of problem is likely to increase as more devices are used to access the internet. Already around a quarter of internet access in the UK is by something other than a Windows PC and this is expected to rise over the next few years. Testing, which is already under invested in, will become more complex over time.
Web users have also become fed up with pop-up windows invading their browsers and taking away control. The number of people downloading software to block pop-ups is growing. Even after testing, there is a possibility the visitor won't be able to use your site.
The bottom line is pop-up windows do have their uses, but their use may upset your potential customers. Any decision to use them should be based on customer reactions, not how pretty the site looks.