I can tell you that the two languages I can confidently say I know well - C++ and Common Lisp - are the ones I learned from books. The rest I learned from various on-line tutorials, articles, references and sometimes from half-reading a book - and while I can code with them, I can feel my coding in them is mediocre. Hell, I feel that the generic-coding skills I have I owe mostly to books (and practice). You can't beat a book in terms of depth and undestanding.

(And don't get me started on videotutorials. This is probably the least cost-effective educational medium ever invented.)

I highly doubt there is any difference, since the only difference is the medium. If a book is published online, it's still a book.

I think you're missing the point. It's not about electronic book vs physical book (If I misunterstood you, sorry and dismiss this post). It's more about the sources on the internet, I don't know many people who read complete books on the computer but rather just read relevant sections somewhere online. While this isn't bad per se, you often miss important details due to different sources (and therefore different views/reader assumptions, ...).

They tend to be very different kinds of books. A comprehensive, deep printed textbook vs. what is essentially nothing more than a tutorial or a collection of practical recipes.

Does reading _Learn You a Haskell_ online make it any less of a book? My point is that "online sources" is a superset of "books", making them incomparable.

No. However a lot of the things I, anecdata, find when I do a google search aren't books, but blogs and random tutorials and stackoverflow.

Books, due to their published nature, tend to have a greater, more thorough, effort put into them. They are generally well laid out, usually well edited, and because people spent money on them the good ones tended to stay in the market and the bad ones tended to drop out.

There's no fundamental difference (except for me, I do much better at recalling things I read from physical books than ebooks), in the source of online versus offline. But it's hard to ignore the difference in quality that tends to happen.

What would be nice, and this is probably done somewhere, would be a reliable aggregator of good online documentation (whether it's an ebook version of a published text or not). Somewhere we can vet and see vetted quality sources of tutorials, manuals, etc.

This is among very few exceptions. Most of the books are still proper books (no matter if they're also available as e-books). Most of the stuff people use for learning online is far below a book quality.

> If a book is published online, it's still a book. reply

Not really arguing the medium of actual books (which is why I specified in my previous post). More a comparison between topic-specific books and blog posts / StackOverflow.