When I want to install Adobe Digital Editions, I am asked for an "Adobe ID". What is it?

Adobe Digital Editions links your e-books to a specific computer. The Adobe ID is a user account with Adobe, the software manufacturer, that is created when you register online. Creating an Adobe ID is free and takes just a few minutes. Just provide a name, your country, and an email address. Only with an Adobe ID can you back up your e-books, copy your e-books to an e-reader or other devices. Create your Adobe ID when prompted to do so when you authorize your computer with Digital Editions, or directly from the Adobe website under "Your Account".