Some websites use target="_blank" in the html to force links to open in a new browser tab or new browser window.
(It is not, as far as I know, possible to specify between ‘new tab’ and ‘new window’. Currently Safari interprets target="_blank" as ‘new window’ but all the other main browsers interpret it as ‘new tab’. In what follows I’ll just say “new tab” for short.)
They may have two alternative reasons for doing this:
(A) is obviously conterproductive. It just pisses the user off with the website. Sites have mostly realised this and (A) is much less common than it used to be.
(B) is genuine. There can be very good reasons for opening a link in a new tab. I do it very often myself, using Shift+Click in Opera (the browser which I use nearly all the time). However, I believe it is a big mistake for a site to try to guess the user’s desires like this.
It makes things unpredictable and makes the user feel they are loosing control
Users want to know what is going to happen when they click on a link. There is no way to tell whether or not a link has got target="_blank" in the html underneath it. So some links will open in a new tab (or new Window in Safari), and it won’t be obvious to the user even after the event what has happened. So if the user thinks the link has opened in the same tab and it hasn’t, they go looking for the back button and find there is no back and waste time wondering why not. Things are worse still the other way round, if they expected the link to open in a new tab and it hasn’t, they may close the tab and completely loose where they were. And worse still if they expected it to open in a new window and it hasn’t, they may close their window and find they have closed down the browser completely and lost all their tabs and sessions.
The Konqueror browser (which is the default browser on Linux) actually interprets target="top" as ‘new background tab’, which gives the user more work to do, to find the tab and switch to it. And if the user wasn’t expecting this and keeps clicking on the link to try and get it to work, they create more and more tabs which they later have to close.
It is unnecessary
If a user wants to open a link in a new tab, they can easily do it for themselves. All browsers let the user right-click on a link and choose “Open in new tab” or “Open in new window”. If they do this themselves, they get what they want and they know what they have got.
[ In Opera it is wonderfully easy to Shift+Click a link to open it in a new tab. Unfortunately the other main browsers do not have this feature. In Firefox, Chrome and Internet Explorer, Shift+Click opens the link in a new window, which is not what I want at all. In Safari it does nothing, and in Konqueror it invites the user to save the file. However, all the main browsers allow the user to do a right-click and select “Open in new tab”. (They also all implement Ctrl+Click to open a link in a new background tab, but since this is a background tab without the focus yet, it is easier to just use right-click in the first place.) ]
If the user sometimes follows a link without opening a new tab and then later finds they want to go back, that is easy too. In Opera I hold the mouse down on the back button to bring up a long list of previous pages, but other browsers have either the same or similar methods. If I want to retain the page I have reached and still go back, in Opera I clone the tab, but again there are ways of doing something like this in other browsers.