Time Machine is Apple’s easy to use automatic backup program built into OS 10.5 Leopard. The concept behind Time Machine is that it’s so easy to use, you just can’t help but use it. Time Machine is well-reviewed and is one of Leopard’s most popular features. It has saved my bacon on several occasions.
To start using Time Machine, all you have to do is connect an external drive to your Mac running Leopard. You’re asked if you want this drive to be your backup drive, and if you say yes, Time Machine will start an automatic backup. Apple goes on to say “You’ll never have to worry about backing up again.”
One of the most common questions we hear about Time Machine is how to hide / remove files from automatic backup. It’s very easy to do this:
1. Choose Apple menu > System Preferences, and then click Time Machine.
2. Open Time Machine preferences
3. Click Options.
4. To specify an item that shouldn’t be backed up, click Add (+) and choose one or more items. You can also drag items to the list. To remove an item from the list, select it and then click Remove (-).
The backup disk is automatically included in the list of items that shouldn’t be backed up.
5. Click Done.
Note that the external drive you’re using for your Time Machine backup is automatically excluded from this list. If you want to back up an additional external drive to your Time Machine disk, you’ll need to open Time Machine and remove it from the list.
Also, note that multiple Mac systems can share the same external Time Machine disk. Each Mac gets its own subfolder, one for every backup performed on that Mac.
Here is a Mac 101 article from Apple about using Time Machine.