The general domain of keeping all your thoughts organized or at least accessible. Also refers to the tools serving that domain.
There’s numerous broad methodologies and tools to guide a PKM system, like BuJo, Zettelkasten, or PARA. The important part is to find / create a note system that works for you, where you can get a thought down and find it later. Steal whatever ideas you can to get your own working system.
My own “system” boils down to a digital journal / wiki where I can get down the day’s thoughts, including the day’s tasks, and refine some of those as distinct topic pages.
I lean towards Logseq for my daily journaling and extracting of useful info, but Obsidian, SiYuan, and Org Mode also make appearances in my heavily ADHD ooh-shiny-thing workflow.