What is the difference between online journals and e-books?

Frontiers’ journals are published exclusively online, with new articles published on a rolling basis. Articles appear on the journal’s main page with links to the full article content and images, accessible at no cost to any reader worldwide.

Frontiers also publishes eBooks arising from Frontiers Research Topics – which are collections of published articles on a focused theme. These can be downloaded for free as PDF or EPUB files from the Research Topic webpage.