If you need to find a file in your Time Machine backups, it’s easy to do. Click the Time Machine logo in the menu bar, then choose "Enter Time Machine". You’ll see a Finder window of your desktop, with others stretching back into the distance, each of which is a backup from the past. To look for files, use the Search bar in the top-right corner of the Finder window. Once you’ve searched, use the timeline on the right of the screen to go to backups further back.

Even if you have Time Machine switched off, you can still use it to back up using the menu bar icon. Click the icon, then click Back Up Now to perform a manual backup. However, it’s best to enable Time Machine’s automatic backups. To set this up, go to Time Machine > System Preferences and switch Time Machine’s status to On. It will now automatically maintain backups of your content every hour for one day, every day for a month, and weekly beyond that.

If you want to restore your hard drive from a Time Machine backup, connect your Time Machine drive and then boot into Lion’s recovery mode (or boot from your OS disc for an older version of OS X). Go to Utilities, select "Restore System from Backup…", choose your Time Machine drive, then select a backup date to restore from. If you made a detrimental change to your Mac before the last backup, you can always restore from a state saved before that.

Time Machine works with several different connections. USB is most common, and will be the cheapest kind of drive to buy, generally, and FireWire 800 twice as fast, so it’s a good option if your Mac supports it. At the extreme end of the scale is Thunderbolt, which is phenomenally fast. Unfortunately, the drives that support it at the moment are really expensive. You can also use Time Machine over Wi-Fi or Ethernet to back up to a Time Capsule.

If you want to resurrect a file from your Time Machine archive, you can bring it to your current machine by selecting it and then clicking Restore. This will put it in the same location on your machine as it was stored originally. If you want to put it in a different location on your hard drive, right-click on it and select "Restore [Name of app] To…". A Finder window will pop up asking you where to place it.

You can move and switch to a new hard drive by erasing and restoring a new drive from your old one. Open Disk Utility and select your new drive in the pane on the left, then click the Restore tab. Drag your Time Machine to the Source box, and the new drive to Destination. Select "Erase Destination" and then hit Restore. Please note that this will erase all data on the new drive.

If you’ve bought a new Mac and want to switch from your old Mac to the new one with everything intact, you can use Time Machine. First of all sort your files and folders how you’d like them, perform a manual backup on the old machine, then eject and disconnect the Time Machine drive. Go through the new Mac’s setup process until you get the option to restore from a Time Machine backup, then connect your new drive and follow the instructions.

Time Machine only works with drives formatted in certain ways, the most common of which is Mac OS Extended (Journaled). If the drive you want to back up to is formatted in NTFS or FAT (or any other formats that aren’t supported), you’ll be prompted to erase the drive, but note that this will delete all of its data. You can format a drive yourself by using Disk Utility, selecting the drive, then going to the Erase tab. Select Mac OS Extended (Journaled) in the format Field, then hit Erase.

If you’re tight for space on your Time Machine drive, and have some large files (such as video files) that you don’t need backed up to it, you can make Time Machine exclude those files. Go to System Preferences > Time Machine and click on Options. Click the + symbol to add something new, then browse to the file or folder you want to exclude. Once you’ve added it, you’re able to see its size in the preferences window.

Should your hard drive go kaput, you can still work on your Mac. If you hold down the å key when turning it on, you can choose to boot from different volumes – and OS X Lion gives you the option to boot from an external Time Machine volume. This lets you access files and apps from a backup computer even if your Mac is misbehaving. Performance won’t be as good when you’re using an external drive, but it’s a great option in an emergency, and provides a familiar environment to work in.