eBook publication follows the same steps as hardcopy book publishing.
Only eBooks do not need a Bar Code.
At the end, the book is used to generate an EPUB file. This is standard for eBook publishing. All compliant eReaders will display it properly. For example, you can read the eBook on Kindle, iPad and Nook etc.
It is therefore advisable to publish eBook as well as hardcopy book together.
eBook publication is important because people prefer to read it on their eReaders.