To Pop Up or Not Pop Up

I recently ran across a fine article by Dey Alexander on opening new browser windows. She summarizes,

Opening new browser windows can confuse or annoy users, so designers should take care when considering this approach. New windows should only be opened when doing so supports users' tasks. And users should always be given a clear warning about what will happen when they click on a link that triggers a pop-up or opens a new window.

It's hard to argue with this. Popups have long been used carelessly and users have been the victims. I not-so-fondly recall a site that opened so many windows (some of them maximized) that participants in our usability test were hopelessly lost. And let's not even get into the subject of invasive advertising windows. Popup blockers are a godsend.

There are situations when popups are very user-friendly, even ideal-when defining terms, for example. On UXCentric, I open every link in a new window; in the blog environment, I think that's best.

I'm not certain I agree with Ms. Alexander's conclusion that it's best to visibly advise users in text that a link opens a new window. Clutter is an arch-enemy of Web usability and we want to keep text to a crystalline minimum. On the other hand, it's user-centered and even polite to let people know when a site diverges from the expected. So here I'm on the fence.

Ultimately, though, the issue is this: Don't open new windows unless absolutely necessary-and vet the decision thoroughly during the design process.

UPDATE (February 11): Douglas van Duyne (co-author of the helpful The Design of Sites) offers his views in To Pop-Up, or Not to Pop-Up, That is the Question. I like what he says.