If you had a time machine and you could go back to any date and time. Where would you go? who would you meet? and what would you be doing?

Setting up Time Machine is as easy as connecting an external drive to your Mac via Thunderbolt, FireWire or USB. You can also use a secondary internal drive if your desktop Mac has one (that is, a drive that you don't start up from). If you haven't specified a Time Machine backup device yet, Time Machine asks if you would like to use the disk for backups the first time you connect it.

Click "Use as Backup Disk" to confirm you want to use the drive for Time Machine backups. Time Machine preferences will then open with this drive selected as your backup destination. Check "Encrypt Backup Disk" if you want to encrypt the Time Machine backup external drive using FileVault 2 (OS X Lion and Mountain Lion only).

Note: If you want to use Encrypt Backup Disk, but the choice is dimmed (grayed out), you'll need to turn on FileVault 2. That's all you have to do for Time Machine to automatically backup your Mac. Open Disk Utility (located in the Utilities folder).

Connect the disk if it isn't already attached. In the left side of the Disk Utility window, select the disk you want to use with Time Machine. Optional: If you want to partition the disk, click the Partition tab and select a layout.

Make sure "Mac OS Extended (Journaled)" is selected in the Format menu for the partition that will be used for backups. Click the Erase tab. Optional: If you want to securely erase the disk, click Security Options to configure, then click OK.

After erasing, open Time Machine preferences in System Preferences and configure as described in the section above. You may want to set up Time Machine in the evening so that the initial backup can be done overnight because it may take a while depending on the size of your OS X volume. You should not interrupt the initial backup.

You can continue to use your Mac while Time Machine backs up. Once the initial backup is completed, Time Machine performs subsequent hourly backups of only the files that have changed on your Mac since the last backup (as long as your backup drive is connected). Tip: You can manually initiate a Time Machine backup cycle at any time by choosing Back up Now from the Time Machine menu, even if you have Time Machine preferences set to off.

You can manually select another backup drive in Time Machine preferences. Note: Every available drive that can be used to store backups is listed. If you’ve partitioned a drive, the available partitions are listed.

Time Machine can’t backup to an external drive that's connected to an AirPort Extreme, Time Capsule, or a drive formatted for Microsoft Windows (NTFS or FAT format). If you select an NTFS or FAT-formatted drive, Time Machine prompts you to reformat the drive. Choose a different drive or reformat the drive in Mac OS Extended (Journaled) format.

Because reformatting erases any files on the drive, only do this if you no longer need the files or if you have copies of them on a different drive. The most common format for a Time Machine backup drive is Mac OS Extended (Journaled) format, but Time Machine also supports Mac OS Extended (Case sensitive, Journaled) and XSan formats. If the drive is partitioned using the Master Boot Record (MBR) partition type, some partitions may not be available for use with Time Machine.

The GUID Partition Table (GPT) or Apple Partition Map (APM) partition types are recommended. Time Machine works best if you use your backup drive only for Time Machine backups. If you keep files on your backup drive, Time Machine won’t backup those files and the space available for Time Machine backups will be reduced.

Hold down the Option key at startup to boot into the startup manager. Select the Recovery system of the Time Machine backup to start from. Once started, you will have all of the functionality of Recovery.