It depends. Some eBooks have unlimited users and will always be available.Some eBooks may only be viewed by one person at a time and will become available soon after the first user closes the book or becomes inactive while using the book. Some eBooks can be checked out like print books and will be unavailable while the book is checked out.
If there are restrictions on the use of the book, when you go to view a book or check a book out, it will tell you if the book is unavailable at that time.
Example of “availability” messages on eBooks:
