With previous versions of OS X, you could have used the installation DVD to fix problems. An emergency drive (also referred to as an OS X Recovery Disk) can help you repair the hard disk, reinstall the operating system, and restore from a Time Machine backup to get your computer back fast.
It’s a good idea to have a bootable emergency drive on hand, just in case disaster strikes your Mac. AirPort Apple Apps Backups Developer Education Email Hardware Internet iPad iPhone Mac Music Network Photos Security TV Weekend Wonk
