When is it acceptable to make clicking a hyperlink open a new browser window?

Does there need to be an indication on the link or image that makes this occur?

What are the guidelines - and why?

+4  A: 

Never. Really. If a client asks for this, talk him out of it.

As for why: because it's bad design. Users don't expect windows to pop up. Browsers don't all handle popups the same. It could get pretty confusing on a small handheld device with limited screen space. It could confuse visually impaired users (those using screen readers). People don't expect it, because they see it less and less. You don't want to surprise your visitors, you want them to have a comfortable, predictable experience.

It was acceptable in the '90's indeed. 'inline' popups (i.e. DOM manupulation) for the benefit of the user could be OK though.

I have a button in my webapp that opens a PDF. In this case i think it has to be a popup because visitors tend to close the window to close the PDF, closing the app alltogether.

I do open it as a complete new browser window however. If you can explain why a popup makes more sense than any other option i'd say why not.

The other option could be to open a div overlay, there are some AJAX controls for that. But it really depends on what you want to do.

+2  A: 

I think never. I don't need a web site to open new windows/tabs of my browser when I didn't ask for it. If I need something in a new tab I will middle click on the link.

Ilya Biryukov

Use modal dialogs instead of popup windows. Popup windows has a tendency of confusing people with screen readers.

Gert G
+1  A: 

Only if there is some message that you just absolutely must show the user. I don't see too many cases where this would be the case. Users don't want to see unexpected popups about errors. Those are just annoying and will likely prevent users from even thinking about coming back again.

So, unless clicking that hyperlink will trigger a bomb and you want to confirm the user's action, then no, you shouldn't do a popup.

+1 "Clicking this hyperlink will cause a nuclear war do you wish to continue?"
"Lets start a war, lets start a nuclear war at the.." Thanks now its stuck in my head.

I think that behaviour should be reserved to sites gathering links to external sites (such /.,digg,). Anyway, you should point it ("open in a new windows"). Otherwise, it usually annoys users.

+1  A: 

Users are pretty savvy these days. They know that their mice have middle buttons and I believe they use them. The browser provides all the controls the user needs to control their browsing experience.

There really isn't a good reason to open new windows or resize windows from javascript today. You gotta stay classy. For executives that insist on these things, here are few lines you can try:

  • Do you want our site look like porn/malware/crack webiste with popups, popunders and tits?
  • Apple/Microsoft/Google/NYTimes don't do it.
  • It breaks the internet and make our site seem outdated.
Igor Zevaka