The word Ebook is an abbreviated way of saying Electronic Book, which is a type of book or manual that can be;

And just like paper bound books, eBooks can be read over and over again, but eBooks don't wear out from use.

As long as the ebook is on your computer you don't have to be connected to the internet to read it, but you may need specific software in order to view the ebook.

The most common type of ebook format is the Adobe PDF and the software to view these types of ebooks is readily available and Free.

When you're finished with an eBook you can simply delete it from your computers hard drive or save it as long as you want for future viewing.