Markdown-based knowledge base
If you would like to organize your tasks and knowledge for documentation, your PhD or just for your day-to-day work, there are two nice apps for this.
Obsidian and Logseq, Logseq is a FLOSS application and I personally always prefer FLOSS to non FLOSS program, IMHO.
Here is an article which explains Obsidian
https://www.linux-magazine.com/Issues/2021/247/Personal-Knowledge-Managers
Here is a delightful video for comparison
Both apps can be use for information management via the zettelkasten method
A link for further reading