A pop-up window is simply another resource for displaying content. Many advertisers abuse them, however, thus giving pop-up windows a bad reputation. They can be implemented in a friendly fashion that won't make your visitors angry -- and they can be very useful in certain circumstances, such as on an intranet. Alejandro Gervasio explains.
Without a doubt, pop-up windows are one of the most controversial topics on the Web. They are the preferred tool for unscrupulous vendors annoying us with "in your face" advertising. Most people believe that pop-up windows are really evil things, and in many ways, this is correct. The main reason to think that way is that pop-ups are nearly always poorly implemented or simply not needed. What’s more, there are a lot of problems related to them, but the most common faults include the following:
Scripting disabled: If scripting is disabled, or if the browser doesn’t support JavaScript, the pop-up will not work. This is known as JavaScript dependency.
Search engine problems: Search engines cannot follow links to pop-up windows because scripted elements are ignored.
Inability to update links: Site management tools (e.g. DreamWeaver) cannot update links to pop-ups if you move the destination page to another section of your site.
Accessibility problems: Pop-ups take the focus away from the main browser window, which is disconcerting for visitors. Also, pop-up windows usually remove toolbars from the browser, including "back buttons," which are key accessibility element for users.
Pop-up killers: Many people run these applications on their computers, and with good reason. Picking up on the general sentiment against pop-ups, some browsers now have options to stop pop-ups from opening in the first place.
The list can be continued endlessly, and you could probably add your own item to it.
However, there are times and conditions in which pop-up windows might be a desirable effect. These situations usually fall under intranet applications rather than websites, where users need to work with browser chrome partially or completely turned off, or page refreshes aren’t necessary. Whether we’re working on intranet projects or building websites, as developers we must be able to address most of the problems associated with pop-ups.
This article will show that, properly implemented, pop-up windows can be used without upsetting most people, particularly the person browsing our site, adding a powerful focusing effect to the contents of our Web applications. Let’s get started!
Design Usability 
