Safari can save a page as a "webarchive." If you find a web item that's important for you - especially for content related to your work or special interests - BE SURE to save the web archive, not the link alone. Webarchive "works" even when a page or site is taken down. Personal experience: In the 2 or 3 months I've just spent on an article which includes some links to relevant sites, TWO of them are now gone. One a whole site that was very well done. The other a portion of MSU's site with contents of an out-of-print but not yet "public domain" book. Found these while double-checking the links the past 2 days before submitting the article. I took the links out of the article, but still can access the information.
"For what is age but youth's full bloom,
A riper, more transcendent youth" - Oliver Wendell Holmes