In general, the safe choice is to open a link in the same window. I can use the middle mouse button to open the link in a new tab if I want, or I can just click on it, read the contents, and press Back. If you make the link always open in a new tab/window, my options are more limited, and I have to close the tab/window when I'm done, then hunt through my tabs to find your site again and continue reading.

I say "in general", because there might be specific use cases where a new tab/window makes more sense. Maybe you expect the user to want to keep both windows on the screen, or maybe you expect the user to spend a lot of time or drill down deep on the external page. It's hard to say without knowing more, but for a regular social news site, my personal preference is for same window.

Social News is one of the features as I mentioned and for some users it might qualify as just a Social News site based on the way they adopt it but for others the Social News feature might be one of the features they will end up using. Our problem is how do we identify the least common denominator without having to do extensive A/B testing?

I'd say only do it if you are targeting an unsophisticated audience. Computer savvy users can handle their windows themselves, but a lot of people can't.

Never open a new window automatically - let the user middle-click.

Several exceptions to this.

For example, links received in email, if you view the email via a webmail client gmail for instance, and click on the link, it will open in a new window.

I think it depends on the % of users that will want to go back to your app after looking at the link. And with ajax type apps, the back button just doesn't cut it.

I don't know about "never." I spend a lot of money getting users to my site (I'm not web 2.0, but rather a downloadable software product). I'm not eager to send them elsewhere. That's one of my gripes about xhtml 1.0 strict: target="_blank" doesn't validate. So, my site is all strict except the links page, which has to be transitional to validate.

It doesn't validate because breaking my preferences and opening a new window which I didn't ask for is (apart from being an obnoxious thing to do) a 'behaviour'.

The "Strict" standard, rightly, enforces a division between content (XHTML), design (CSS) and behaviour ({Java|ECMA}script).

If you want links to open in external windows, attach a behaviour to the link class with JS. Just make sure that behaviour is off by default, though, because otherwise people like me who know what we're doing won't use your site.

I don't use JS on my site, because others won't use the site with JS. The link page is the only page on the site that does this, so I'm going to go with it.

It's not obnoxious if you consider that some people really don't understand how the web works or what the difference is between sites. In that case it's a convenience.

This is an idea which should be left as a "best practice," but allow for reasonable differences.

I hate it when links force a new browser window or a new tab. Users are smart enough to hold down shift or control when they click to get a new window or tab, aren't they? Why not have an option people can choose to have external links open in a different window or tab?

Never open windows in a new window. Users know how to click the back button if they want to come back to your site they will. I also believe its not part of WC3 validation.

A meta-suggestion: avoid lengthy discussions about such issues. Pick one option quickly, then run experiments to test whether the alternative improves your relevant metrics. Some issues are too small to invest time in trying to find 'consensus' without hard data.

On the issue directly: the web default is to open links in the same window. Opening new windows is in Jakob Nielsen's list of the top ten very worst web design mistakes†. (It's #9 as of his 2007 update.) So skip the discussion, go with that, and later run some tests comparing stay-in-page with open-new-window on whatever metric is important to you. (Page views? Non-annoyed users? Return visits? etc.)

† http://www.useit.com/alertbox/9605.html

Exactly. Spending more than five seconds on this (before you have data), and even worse, involving more than one person, is a recipe for fail.

People just love to argue about silly shit like this.

Homework assignment for everyone who felt compelled to chime in with their well-reasoned opinions:

http://www.bikeshed.com/

You should open the urls in the same window. Because thats what most of your users will be expecting, considering most other sites do that. So by habit, they'll either use the middle click button or some other way to open it a new tab or window.

Don't override the default - even if it seems broken it may be required for compatibility. To paraphrase Tim Berners-Lee, fix your client, not the web.

Here's how we do it.

http://domain.opendns.com/thejack.humboldt.edu

With the icon... and some text.