Online publishing or electronic publishing means publishing e-books and electronic articles as well as development of digital libraries by way of the Internet. Online publishing is fast becoming a popular mode of disseminating all kinds of publications. Most of the information is encapsulated as e-books, which are electronic or digital versions of printed books. The term e-book is an individual work in a digital format or a hardware device used to read books in a digital format.

Online book publishers commonly bundle information as e-books for distribution among target users. Most of the e-books contain metadata like printed books and includes details about author, title, publisher and copyright date. Online books can also be published in a variety of formats, keeping target readers in view and the type of work to be digitalized. Some of the commonly used formats are image, used mainly for distributing comic books, art books or other visual works; rich text; hyper text markup language or HTML, used mostly in web pages; PostScript or .ps is a page description language used primarily in the electronic and desktop publishing industry for enhancing the quality of a printed page from the actual output of bitmap file.

Other advanced formats include TeX, used as a popular academic format; Portable Document or .pdf file format, created by Adobe System to provide a standard form for storing and editing printed publishable documents; eReader, a program for viewing Palm Digital Media electronic books; DesktopAuthor, an electronic publishing suite that allows creation of digital web books with virtual turning pages. Digital web books can be written in this format, including e-brochures, e-books, digital photo albums, e-cards, digital diaries, online resumes, quizzes, exams, tests, forms and surveys.

Online books undoubtedly score over the traditional printed books as they are less cumbersome, distributed at a low cost, can be formatted and copied easily, have less margin of error and give more editorial and authorial freedom. However, online book publishing has its own share of problems, as e-books can be easily hacked or disseminated without approval from the author or publisher.