Links to external pages like in this thread:
open the link in the same window as the forum.
I would prefer that such a link would open a new tab folder or a new browser window so that it would not be necessary to use the "back" button to return to the forum topic.
Just hold down CTRL while clicking on the link.
Yes, or right-click on the link and use "open in new tab or window" ... I was talking about the default behaviour.
You can change that at according to your personal preference at
Preferences > Interface > Open all external links in a new tab.
Or you can click such a link with your mouse wheel (if you have a mouse with a clickable mouse wheel 
)
For german users:
Einstellungen -> Oberfläche -> Andere:
Öffne alle externen Links in einem neuen Tab
AKTIVIEREN und Speichern
That was helpful. Thanks
But: these settings only apply for logged in users.
If you are a guest, then a link opens in the same window/tab...
Because a lot of websites I visit open a link in the same window I made it a habit of mine to click with CTRL, if I want a new tab.
This is easier than to remind which websites opens a new tab and which not.
Depending on your browser you can get pluggins to take control of this. Some let you set up the MMB (middle mouse button press) behavior as you want.