Matt Cutts: I’m really glad that somebody asked that question. The original reason for recommending 100 links per page was pretty simple; at one point Google would only index 101 kilobytes per page and so we needed heuristic to say, “Don’t make a page so incredibly long that we’ll truncate it and not index the words at the end.” So we said 100 kilobytes and 100 links is a pretty rough measure but it you’re getting much beyond that it’s a little unusual.
But that 100 links per page guideline dates back 8 or 9 years. The web has changed and web pages tend to be a lot more rich. They tend to have a lot more information on them if you go back and compare now vs. 10 years ago for average pages on the web.
So if you look more carefully I believe that we have removed the guideline that says 100 links per page. Now does that mean that you should go in and instantly throw 5,000 links all on one page? That’s probably not going to be a good idea; not only because it’s a bad user experience but it might look like a link farm or like you are stuffing a bunch of links in there. But I wouldn’t necessarily stick to the idea that there has to be 100 links on a page.
That was always in our technical guidelines, which means we are not going to consider it spam if you have more than 100 links but we might not index all of them. But we have removed that guideline and now it’s entirely reasonable that a rich page can have quite a few links before you really have to worry about running into any sort of issue where we might not follow every single link.
One thing to be aware of, we do take the PageRank of a page and the PageRank equation says you divide by the out degree. So if you have 500 links on a page you are dividing the PageRank of that page by 500 when you look at the outgoing links. That’s according to the original PageRank paper.
So that’s one thing to bear in mind. You might not want to automatically go for hundreds and hundreds of links or a thousand links but think carefully about which pages are really important and then try not to overwhelm your users with links that don’t give them a lot of value or benefit.