In the broad sense, an electronic book, or e-book, means published content that is stored in the form of digital data on any kind of electronic storage media, such as a hard disk, floppy disk, optical disk or IC card, and transmitted through a data network to the user's digital reading equipment, such as a PC, notebook, PDA or even a mobile phone.
廣義的電子書，指的是透過電子數位系統，把出版內容的數位資料存放在各式電子儲存媒介如硬碟、軟碟、光碟、IC 卡等，再透過通訊網路把數位資料傳送到讀者的數位閱讀設備，如個人電腦、筆記電腦、PDA，甚至手機等。