This pane appears only if your Mac does, in fact, have a DVD drive. It lets you tell the Mac what it should do when it detects that you’ve inserted a CD or DVD. For example, when you insert a music CD, you probably want iTunes to open automatically so you can listen to the songs or convert them to MP3 or AAC files on your hard drive.
For each kind of disc (blank CD, blank DVD, music CD, picture CD, or video DVD), the pop-up menu lets you choose options like these:
Ask what to do. A box asks what you want to do with a newly inserted blank disc.
Open (iDVD, iTunes, Photos, DVD Player…). The Mac can open a certain program automatically when you insert the disc. When the day comes that somebody writes a better music player than iTunes, or a better digital shoebox than Photos, then you can use the “Open other application” option.
Run script. If you’ve become handy writing or downloading AppleScript programs, you can schedule one of your own scripts to take over from here. For example, you can set things up so that inserting a blank CD automatically copies your Home folder onto it for backup purposes.
Ignore. The Mac won’t do anything when you insert a disc except display its icon on the desktop. (If it’s a blank disc, the Mac does nothing at all.)