Related Pages
Help with Burning Video DVDs (DVD-Video)
Getting Nero and Burning Video DVDs with Nero

Multisession Option in Nero

Multisession (or multisessioning) is a term for being able to add more to a disc later. A multisession disc is a disc burned in more than one or several successive sessions. You don't need to use a rewritable disc in order to multisession.

I'm quite sure that the following is true with most disc-burning software:

You can burn multisession data CDs and data DVDs;
You can't burn multisession audio CDs;
You can't burn multisession video DVDs (DVD-Video).

In my experience, in Nero, if it's possible to burn a multisession disc, Nero automatically asks you, near the end of the burn process, whether you want to be able to add more to the disc later. Say Yes to that if you want to multisession.

The following setting might be necessary if you want to be offered the above multisession option:

Click on Start;
Go to All Programs;
Go to Nero (or Ahead. then Nero);
Go to Data;
Click on Nero Burning ROM;
Click on the Multisession tab;
Select the radio dial Start Multisession disc.

The above setting should remain unless you manually change it.

This is what a Nero help topic says about the multisession option:

Enables the option to write additional files to the CD/DVD. The CD/DVD is not finalized.
Multisession CDs/DVDs do not have to be written in a single burn process. You can burn projects repeatedly to a CD/DVD until it is completely burned.
Not available for Audio and Audiobook CDs or when saving with Nero Image Recorder.