I made a simple experiment about six months ago. And discovered the flip-side of the coin. Here are the exact steps I took:
- I have a page that ranks on top of Google's SERP. It's our Macro Recorder homepage. I've put a lot of effort to get it there and it took us five (5) years of hard "white-hat" work to rank high on "macro recorder", "mouse recorder", "macro program", "keyboard macro" and all the variations.
- I've put an external link on that page - linking to a Wikipedia-article on the very same topic - "macro recording". It's a highly relevant link, obviously. And what can be more trusted and authoritative than Wikipedia?.
- Boom. In one day the Wikipedia article has outranked my page in the SERP.
So be careful.
I guess in my particular case the reason was as follows: domains like Wikipedia are much, much more "trusted" and "relevant" in Google's eyes, that's why adding one tiny link to it's macro-recording article rocket-launched the article outranking my own page.
Removing the link restored rankings back to normal. But it took several days.