There have been several studies over the years which have demonstrated that Google appears to rank pages more highly if they contain links to external sites. I’ve drawn attention to those findings here, and I’m sure that long-term readers will take this for granted.
Recently, however, Google’s John Mueller has made a couple of public comments saying that external links are pointless unless they’re genuinely helpful. I suspect this means that very few external links actually benefit a page’s ranking. He wrote: “Treat links like content. Does this link provide additional, unique value to users? Then link naturally. Is this link irrelevant to my users? Then don’t link to it. Name-dropping a dictionary doesn’t fix your spelling mistakes.”
In other words, if there’s background content that users need to know, but which can’t be included for reasons of space or universal applicability, then we should definitely link to it. But underlining every other noun just to make it seem like an article is well-researched won’t gain us anything. Just ask if the link is answering a question that some readers might have while reading the piece – a question which could be: “Can you back up that statement with evidence?”