target="_blank"
target="_blank" opens a hyperlink in a new window (tab)
As I have been adding back some external links to pages when I have inplemented a keyhandler I have noticed how this can both be useful and very annoying. Wikipedia do not do this for obvious reasons as you would end up with far too many windows open as you click from page to page. However, when performing research it is useful to do this.
So far this seems to be working well for me.
StackOverflow
The discussion on StackOverflow about opening hyperlinks in a new window/tab is quite interesting. I think it is safe to say that there are pros and cons in doing this.
From a personal point of view opening external links in a new window works well as I know that I have to close these windows and it allows me to have multiple reseach pages open at the same time and I can also return to the page that I was referencing them. For an external visitor not opening an external in a new window will almost certainly mean that the visitor will not return to the page that took them to the external page. This is not that I am so precious and want to do anything to prevent a visitor leaving my pages. I might also add that most commercial websites do not have links to their competitors for example.