Users of Apple's Mac OS X 10.5 (or above) operating system have the option of using Time Machine with an external hard drive. Time Machine is an easy-to-use and completely automated incremental backup for your computer. This page covers getting a drive setup to work with it. For usage instructions use the Help menu on your computer and search for Time Machine.
As soon as OS X detects an external hard drive attached, it immediately asks if you would like to use it with Time Machine.
Clicking Use as Backup Disk will automatically enable Time Machine and begin the initial backup of your computer. You can also tell it was successful because your hard drive icon has inherited the Time Machine icon.
If you've previously declined to use your external hard drive for Time Machine and now have changed your mind, you can enable it via the Time Machine System Preference.
Time Machine is only intended as a backup & data recovery service for the computer it is installed on. If you get a new computer that is a different model, Time Machine may restore the entire operating system to it, but due to differences in hardware, your new computer may not boot or have problems with some of its features. CTS does not support restoring a Time Machine backup to a new computer.