Re: TYVM!

So, do you recommend that one opens a new tab for every link, or just URL shorteners and socnet?

Every link. At least every link where it would be relevant not to reveal referrers.

URL shorteners and socnet shared links are just more likely to integrate the redirection in the URL itself, for instance:

[true URL]?utm_source=dlvr.it&utm_medium=twitter

This gets added automatically by shortening and sharing, and traces you to dlvr.it and Twitter.

But the referring can also be done by script (if the links are not on plain HTML) - and the browser can also be leaking it (as Griffith said). So it is ultimately more convenient to open a new tab always unless it really really doesn't matter.

Is there a way to know or find out if an website does referring?

I don't know 100%. Reading the code you can see it, but of course this is not practical for everyone - especially if the relevant code is not easily visible.