See here for the idea behind writing kata.
The novice asked the master, "what things have the bookmark nature?"
The master replied:
Bookmarks, of course. Bookmarks that live in apps like raindrop.io or pinboard. App specific bookmarks, like the YouTube "Watch later" playlist.
Open tabs that aren't related to a task you currently have plans to work on. Starred or favorited items, depending on the app's semantics — 𝕏 likes do not have the bookmark nature, but github stars might.
Wishlists inside shopping apps are bookmarks, as are shopping carts that you're not acting on.
Apps you're not using but have installed are bookmarks, whether they be on your phone or computer. Similarly, plugins that you have installed but don't use are bookmarks.
Saved emails are bookmarks, doubly so if they're inside a folder structure. PDFs and books you've downloaded and will read "someday" are bookmarks, doubly so if they're in calibre. Zotero citations are bookmarks.
Your photo library is nothing but bookmarks. The notes you save in your app are bookmarks. Your todo list is full of bookmarks. The photos and souvenirs in the box in the closet are bookmarks; the notes stuck to the fridge are bookmarks, as is the todo list right next to them.
Everything you own and are not using regularly is a bookmark: the PDFs you print, the books you bought and haven't gotten around to, the materials for the project you'll get around to "one day," the specialty tool you own whose day has never come, the box full of cables in the basement, the raspberry pi on the nightstand, ...
Several more minutes passed as the master went on. Finally, the student found room to interrupt, and asked the master: "master, what is the bookmark nature?"
The Bookmark Nature
At this point, I've been thinking about bookmarks for decades, and I finally feel like I have some understanding of what their underlying nature is. The name derives from a marker used to track progression through bound volumes, but ironically, in almost every case in the digital realm, "bookmarks" don't track progress.[1]
A definition of bookmarks
To a first approximation, bookmarks are aspirational reminders of future selves you may want to be. That's it.
A useful flourish here: "aspirational" means that bookmarks are things that do not currently have a job. There are some bookmarks that do not have the bookmark nature, like, well, book marks. (Also, the todo list that is short and engaged with; the active shopping cart; the book you're reading, the project you're researching now, ...)
When I bookmark a page that talks about something I didn't know, or want to learn, or that talks about a habit I want to develop — that means I want to be the sort of person who knows things, or does things.
When I bookmark some nifty gadget, or some new clothes, or a product — that means I want to be in a situation where I those things are useful, or I can afford those things.
The analogy can get a bit tenuous — some healthy bookmarking, and a lot of unhealthy bookmarking ("hoarding") falls between "loss aversion" and "mental illness" — but even for things like photo rolls and souvenirs, there is an "I want to be." I want to be the sort of person who remembers their past, who can make a photo album that's touching, who can find the perfect meme at just the right time...
A possible refinement
However, if you're not satisfied by the first approximation, then the second might satisfy you: bookmarks are a way to emotionally regulate, and ground your identity. It shouldn't take much effort to see how the cables in the basement and the photos in the closet fit into that definition.
And, when you look at both of these definitions, you might understand why most of the most productive people are dismissive of extensive bookmarks, of note taking "systems," of having too much "stuff" — because doing, and being, and being present in the moment, don't need bookmarks.
That is, when you bookmark a webpage, the browser does not take into account where on the page you stopped reading. This happens to words quite often; I go back to the word "antenna," which originally referred to a sail yard, but transferred to insects based on physical similarity, then to electrical antennas based on physical and sensory similarity, then to tiny fractal chips on your cellphone based on sensory similarity. Most modern antennas bear no resemblance to a sail yard! ↩︎