Link rot
Over the years this site has gone through many incarnations as I have changed platforms; Hugo, Pelican, WordPress, MovableType, and so on.
One by product has been that some of the internal links between posts, journal articles, what have you, became broken because of the variety of ways of referring to pages. In the past I have done the occasional sweep to try and fix these. Over the past couple of days, I have been fixing most of the broken internal links and some of the broken external links.
Using https://www.brokenlinkcheck.com/ I see that I still have several hundred broken links to fix, and I am slowly working my way through them.
For the links to external pages that no longer exist, I am trying to used the appropriate copy archived by the Wayback machine.
Of course sometimes, that is not possible. Either the Internet Archive does not have a copy, or the sites robots.txt file. At that point, I just leave the link pointing to the original—now missing–source.