We have two tags for books and online-resources, whose primary purpose seems to be to denote a type of thing. I'm not really sure what the intended use of these is, but what they are being used for is all over the map.
Online-resources had been used for all of the following (I've cleaned most of it up):
- As a synonym of tools. This was easy to fix.
- Along with a system tag, because someone was looking for some reference that they thought was online instead of in a book. This has been very inconsistently applied, and doesn't really add anything even when it is applied (almost never is the person trying to say "I won't accept the answer if it comes from a book).
- Someone is looking for something online. Sometimes something has its own tag, like art. Sometimes it doesn't. The tag for something seems to be the only useful one here, unless online-resources is meant to mean "collection of unrelated stuff that happens to be online". Far as I can tell, that doesn't actually happen.
- As a catch-all for otherwise unrelated things that happen online, but may or may not belong in tools or online-roleplaying.
Similarly, books has been used:
- Where can I find old books? (These have been closed when they pop up.)
- Along with a system tag, because someone was looking for some reference that they thought was in a book and can't remember which one it is. Once again very inconsistently applied, and once again I've never seen any case where a person would reject an answer if it came from an online source instead.
- Comparing specific versions of a book for changes.
- Questions like "What benefit does owning physical books have?".
You'll note that #2 on both lists are basically the same thing, the only difference is where the person asking the question thinks the thing they're looking for is. Given that the person in pretty much every case is just looking for the answer and doesn't actually care if its in a book or online, that's largely pointless. It's also very inconsistently applied, making the tag not reliable for that purpose.
In general, I don't think either of these tags is doing a whole lot that's useful. They're overly broad, generally inconsistently used, and don't really add any kind of useful organization. There's a couple of cases where we have nothing better, but that should be a matter of creating tags to more accurately reflect what's being asked, rather than saying "this thing is about something that happens to be online, so it gets an online tag."
Kind of a huge amount of the answers on the site rely on things that are either online or in a book, and most of them are not tagged with either of those things. online-resources in particular is a really useless distinction, as it's a collection that has nothing in common except the Internet is involved somehow.