Q: time capsule

You should be using an external hard drive with a total capacity of about 2-3 times the total capacity of the computer's hard drive. It must be formatted Mac OS Extended, Journaled.

The "Book" on Time Machine (Mountain Lion)

OS X Mountain Lion: Time Machine overview

Mac Basics: Time Machine

iTunes 11 for Mac: Time Machine

Mac OS X: Time Machine Basics

OS X Mountain Lion: Time Machine preferences

OS X Mountain Lion: Time Machine problems

OS X Mountain Lion: Time Machine configuration preferences

OS X Mountain Lion: Time Machine options preferences

OS X Mountain Lion: If Time Machine is slow

OS X Mountain Lion: About the Time Machine backup password

OS X Mountain Lion: Back up files with Time Machine

OS X Mountain Lion: Exclude items from a Time Machine backup

OS X Mountain Lion: If a Time Machine backup is interrupted

OS X Mountain Lion: Disks you can use with Time Machine

OS X Mountain Lion: Restore items backed up with Time Machine

OS X Mountain Lion: Pause and resume a Time Machine backup

OS X Mountain Lion: Recover items using Time Machine and Spotlight

OS X Mountain Lion: If Time Machine doesn’t back up certain files

OS X Mountain Lion: If Time Machine can’t find your backup disk

OS X: Cannot install on a volume used by Time Machine for backups

OS X Mountain Lion: If Time Machine remains in the “preparing” stage

OS X Mountain Lion: If your Time Machine backup disk runs out of space

Time Machine: How to transfer Time Machine backups from one Time Capsule to a different one

Time Machine: How to transfer backups from the current backup drive to a new backup drive

Mac OS X v10.6: Issues after restoring a Mac from a Time Machine backup made with a different Mac ("Restore System From Backup…")

The Second Book of Time Machine is: Pondini's Time Machine FAQ for help with all things Time Machine.

No. A CD-RW is an optical drive using optical discs. It is not suitable for a large backup because it does not have sufficient storage space. A Time Capsule is an Apple device that contains a network router and a hard drive to make up a Network Attachable Storage, NAS, device. It is used for Time Machine backups and acts as your network router to connect to your cable modem as well as to provide a wireless network.

An external drive is just a hard drive in an enclosure that connects to your computer by USB or Firewire cable. It is directly connected to the computer. Here are some examples.