(Surprised I didn't already find an answer here to this!)

I've got a computer on which I'd like to back up the iTunes library – music, movies, apps, everything. We're talking multiple gigabytes.

Unfortunately, it seems that iTunes' own built-in "Back Up to Disc" feature (the only backup feature I can find in iTunes) only functions with a CD or DVD writer/burner. The computer in question does not have a DVD burner. While it has a CD burner, attempting to back up to CDs would require dozens of discs plus more time than I'm willing to spend swapping them. So:

What is the recommended way to back up an entire iTunes library on a Windows computer, to a non-CD/DVD location such as an external hard drive or a network shared folder?

Then, once such a backup has been performed, what is the process for restoring the library – e.g. after the computer has been repaved with a new version of Windows – so that iTunes is resurrected whole and recognizes devices it syncs with?

Thank you!