A plain-text personal knowledge management system.
I use org-roam for my PKM (note-taking, digital garden, etc). Pretty much all of my digital garden is made using org-roam in fact. I started using it in March 2020.
I love it.
It is a note-taking tool for networked thought. The tool encourages a non-hierarchical note-taking workflow. With Org-roam, note-taking becomes effortless and fun: write notes wherever you want, and link them up however you want.
Some of my customisations of org-roam are here.
One downside, or at least something to mull upon - org-roam doesn't make much use of org's heading structure. It's all file-based, each note is a file. No problem with that right now, just it goes a little against how org mode tends to work?