Google Bookmarks. And I'm a long-term, heavy user. Trying Saved.IO free version as an alternative.
https://screenrant.com/google-bookmarks-shutting-down-when-alternatives/
You're right - I've never heard of it
I use it a lot. If I think the source page will disappear (ex: classified ad, blog post) I put the salient info in the notes section. GREAT for research.
Saved.IO has the same basic features --notes and categorization being must-haves. But the provided bookmarklet didn't have categorization on-the-fly. I found an alternate one that does;
https://codepen.io/wuz/full/nwjqK
I've been using Pininterest.in. Its not free but its reasonable.