Ebook

I guess is the best source to find out this answer. They spell it eBook….

….although it seems as if the format the file is in also affects the spelling.

E-book
Published as a “.doc” or “.txt”

eBook
Published as .pdf or .html

Don’t ask me why!

The word is a neologism, so the ruling may be up to the dictionary writers, the lexicographers. You might write to James Kilpatrick who has a syndicated column on the English language, its grammar and syntax.

My own preference is for it to be NOT capitalized, but with a hypen. This is the clearest representation of the meaning of the word. It should NOT be capitalized, as it’s not a proper noun. If it is part of a title or at the beginning, it would be capitalized.

I don’t like the word, so I might use something else. A book is a book is a book, no matter whether printed on paper with ink or stored in a more advanced medium.

Doesn’t really matter as long as someone understands what an e-book is. It’s a fairly new construct, and just as with email, I would argue there is not only one correct way to spell it, as long as your reader knows what you’re talking about. It depends a lot upon the context. Basic rules apply — titles and proper nouns are capitalized, other nouns are not. So, in a title, E-book or Ebook and in a sentence, ebook or e-book.

Ultimately, it may be best to be very clear and not use the coined word at all.

eBook. Even if the computer tells you its wrong, it is right, even at the beginning of a sentence.