It may be relevant for context that by HN standards I am Old -- a little over 50 -- so I've had some time to accumulate (a) books and (b) enough money to afford a house with enough wall-space for those books to fit comfortably. :-)
Mathematics: John Conway's "On Numbers and Games". (If you've run across the term "surreal numbers", this is the original source. Absolutely gorgeous, but heavy going if you aren't actually a mathematician.) David McKay's "Information theory, inference, and learning algorithms". (What it says on the tin. Don't expect this to be a practical guide to training neural networks or anything like that; it is a mathematics book.)
Philosophy: Derek Parfit's "Reasons and Persons". (Contains some exceptionally clear thinking on thorny questions about personal identity and the like.) Gary Drescher's "Good and Real". (Drescher is primarily a computer-science-and-AI guy rather than a philosopher. He addresses a bunch of hairy philosophical questions from that perspective and I personally like it a lot. I confidently predict that some people will hate it.)
Science: Gnaedig, Honyek & Riley's "200 puzzling physics problems". (Just what it says. Roughly undergraduate-physics level, some easier, some harder.) Steven Vogel's "Life in moving fluids". (Explores, e.g., the very considerable differences in what living in water means for a bacterium and for a whale on account of their different size. Fairly technical; he has other lighter books.)
Computing: Donald Knuth's "TeX: the program". (A single volume of literate code, constituting the whole of his TeX typesetting system. The style is pretty old-fashioned but he's a genius.) Steven Skiena's "The algorithm design manual". (This would not be my recommendation if you want just one algorithms book; that should be Cormen, Rivest, Leiserson & Stein. But it's an excellent complement to a more standard sort of algorithms book.)
One of my personal favourite in Philosophy is "Finite and Infinite Games" by James P Carse. It had a profound impact on how I look at situations. I hope one of your suggestions does the same :)
Leftmost column is mathematics. Next column is mathematics shading into computing (the top shelf is numerical analysis and the like). Next column is mostly physics and physics-adjacent science, with some psychology/neuroscience at the bottom. Rightmost column is other science.
There's another smaller wall with economics, business, finance, history, politics, social commentary, miscellaneous humanities, philosophy, religion[1], and reference books.
[1] I'm not an adherent of any religion, but for many years I was and I have retained a little interest in theological matters despite now thinking that the religion in question is wrong about pretty much everything.
Fiction is in the bedroom and on the landing. Other subjects are elsewhere (e.g., music is in the same room as the piano; language and books-about-literature are in the guest bedroom).
Books with their spines facing up instead of out are ones I haven't read yet. I don't guarantee that I have read every page of every other book, though.
The presence of a book on those shelves is not necessarily an endorsement. I have some books I don't think are very good but that I don't dislike enough to throw them away :-).
(There isn't actually anything super-secret displayed on the monitor but I thought I should censor it as a matter of principle. The other thing that might look like an information leak is the front of a DVD box, but that happens to be a box with no actual DVD in it and I don't even remember why I have it. :-) )
Of the fiction section, most of it is in English, with some Dutch (obviously, being Dutch) and German as well. About half of the fiction is science fiction or fantasy; from classics to modern. The other half is a collection of all sorts of literary works; featuring plenty of classics, but also more recent works.
A full wall¹ of our living room is shelving for books. One thing we are particularly happy with is that since building this bookcase we've had a child who at three now knows no better than that reading is completely normal and a pleasant diversion. Despite not being a reader himself yet, he does consume books at a good rate, either being read to or just browsing the picture books by himself.
1: Photos from just after building it: https://twitter.com/jdhoek/status/885499829052485632
For a more interesting story, look to the origins of the Warburg Library in London [0]: the eldest heir of a wealthy banking family passed on his considerable inheritance on the condition that his brother would purchase any books in any quantities that he wanted. This incredible and unclassifiable collection of 6000+ primary source books, which formed the basis of its owners' incredible and unclassifiable historical research, can still be consulted today [1].
[0] https://warburg.sas.ac.uk/library/about-library/library-aby-... [1] https://en.wikipedia.org/wiki/Aby_Warburg
I've moved approximately 10 times across 3 countries, and my books travel with me. They form the bulk of the weight of my belongings -- fortunately I always worked for multinationals and moving/packing costs were always fully covered as part of my relocation packages. I think I had 40-50 boxes worth of books for my last move.
I own e-books too but I'm not a big fan because I get distracted too easily by digital devices and am not able to muster the deep attention needed to get through a book. So I read paper books. I usually have 1 in the bathroom, 2-3 in the car that I take with my to cafes and restaurants, and 2-3 that I read in my living room.
I don't finish all the books I start -- I'm an incorrigible book non-completist. But I usually manage the extract enough value that I don't really need to finish. Most modern books are 80% fluff written to satisfy book publishers. The core message can usually be conveyed in around the length of an essay.
Some books I keep for nostalgia, such as The Art Of Electronics, which was life changing for me. But I'm trying to be more selective of those books.
I read a lot of fiction, history, biography. Some of those books I get as gifts, and try to pass them on to another reader. I try to make use of my public library when possible, because I still do prefer reading from a book rather than electronically.
I've moved most of my sheet music to electronic. That's an area where technology is actually an improvement.
These days I gravitate towards having them in digital form because that's far less waste of space. Years ago though, all my books were in paper format, mainly paper-back, but quite a lot in hard-cover. I prefer my reference books to remain as a physical book.
Several years ago, I made a conscious effort to replace as many physical books as I could with their digital equivalents. (I also did the same thing with my CDs and DVDs) That probably reduced the space taken up by 'stuff' down to about a quarter of what it had been previously.
About 75 of them are programming related, books I bought or school books that I kept around. The majority of those are digital books though. The rest is a mix of language learning, personal development and some philosophy books.
I think in the future I'll probably throw out a lot more, because I barely re-read anything so it just takes up space. And I'll probably move to more PDF books if I can find them in that format instead of some proprietary e-reader format.
This year I want to read The Brothers Karamazov, 1984 and I'll probably end up re-reading Marcus Aurelius' Meditations again, I end up re-reading most of that every year.
My ebook library is much bigger. Several hundred to low thousands depending on whether stuff like individual comics count. I don't currently have it well organized and in one place. There's also the question of whether PDFs of books I downloaded from the library count as books I own? (Some never expire).
There's a mix of reference material and recreational but it's mostly recreational, at least stuff I purchased. I'm still not satisfied with the state of ePub textbooks so I'll only buy digitally as a last resort option.
For books, I mostly go digital nowadays, but, I make exceptions for:
- "books I want on my bookshelf",
- "books that changed my life",
- books that I just found while looking around in a bookstore.
So far, my bookshelf has classics, novels I really liked, some nice reference books and textbooks, and a few nonfiction books. I am usually more reluctant to stack up on nonfiction physically; they usually get summarized and put into Evernote as points to be looked back at later.
Either way, I strongly feel that everyone has their own unique "bookshelf", collections of books they live by. So asking others would definitely be interesting. Looking forward to the other responses. :)
ebooks are very available if you know where to look and much easier to lug from city to city.
I like the idea of having a wall full of books ,not for bragging, but glancing at the shelf once in a while, reading a few pages of a book you read long back when you are bored is a good way to remind you of the book's theme and what you gained from it. Sort of like browsing youtube and it serves up this scene from a movie you watched long ago. Plus, it does tend to attract a visitor's attention and might start an impromptu conversation.
I got tired needing bookshelves everywhere, and liquidated most of my collection in a big garage sale. That was a really fun, like a day-long bookclub meeting. All I have left are my favorites and, ironically, the ones nobody wanted to buy. Maybe a few shelves worth.
https://imgur.com/a/kBqCxVb Imgur is currently down, but those are my shelves and workspace.
Also, why aren't more people sharing photos? Bookshelfporn is a thing.
The number of physical books is quickly decreasing, though. I'm giving out most of the read ones to charity and libraries since I completely drank the eBook kool-aid.
Since a good portion of my books tend to be technical, there is an annual purge of books that have become outdated. But somehow the shelves remain quite populated.
Audiobooks as of today 325.
ebooks as of today 329 in my two ebook readers.
Probably around 70 - 80 books on data, programming and technology in multiple formats in my cloud storage.
I read/listen to fiction and non fiction alike. As well as a few podcasts.