All eBooks are Digital Rights Management (DRM) free means no restrictions on the number of users, downloads and sharing in a license agreement.
eBooks are available in PDF and sometimes EPUB format.
Both formats can be used and read on various digital devices, including mobile phones.
EPUB is designed for reflowable content, meaning that an EPUB reader can optimize text for a particular display automatically.
PDF content is static; pages are displayed identically across devices.