Yes, it’s common practice to have links that leave your site open in a new window. The rationale is that it’s easier for folks to come back and finish what they were reading on your site once they finish elsewhere.
This is wrong for a number of reasons, thrashed out a decade ago by a dozen of the world’s leading experts in User Interface Engineering, the science of, essentially, how to present stuff on the web. Though all our tools have grown and changed in the past decade, human psychology has not. (When there’s a serious upgrade to the human mind, you’ll know without me telling you.)
Here’s why it’s bad form to force links to open in a new window:
- It is ultimately unhelpful to do something for a user which they can do for themselves. — Users can CTRL-click (PC) or COMMAND-click (Mac) to open a link in a new window. They can right-click (PC) or CTRL-click (Mac) for a popup menu which, among other commands, includes “Open in a new window”. Don’t do things for users which they can do for themselves. I contend that one reason so many people still don’t know how to open links in a new tab or window after a decade of tabbed browsers is that inexperienced designers adopted the practice of doing for users what they should do for themselves. This is like cleaning your teenager’s room for them because they never learned how to do it themselves. It’s also a bit like slicing up your date’s steak for them. Unless you know, absolutely, they want their steak sliced, perhaps it’s best to back off.
- It breaks the browsing history. — Opening the link in a new window starts new browsing history. The back button no longer goes anywhere. Had they accidentally opened the link the same window and wanted to get back to where they were, it’s there. And if they don’t want to go back to your site, they don’t have an extra window to close. Leading to my third point.
- Your users are more important than your stats. — Opening links in a new window because a visitor might wander off and never come back to your site is, in a word, selfish. This is like keeping someone’s socks to ensure they come back to visit you again. If they want to visit, they’ll visit. If they don’t want to, they’re out a pair of socks; er, have an extra open window, and you gain nothing useful.
I don’t remember the last time I set a link to open in a new window. Unless you have a reason which overrides giving your visitors choice and using the tools as they were designed by leading experts, links should not be explicitly set to open in a new window.
Breaking how something was designed in order to make it easy for people to not learn how to use the tool correctly is a bad idea, even without a plethora of usability experts to tell us so.