Time Machine is a backup feature developed by Apple and integrated with OS X. To perform your backup, you must have an external hard drive with no data. Start by connecting your external hard drive to your Mac and start Time Machine: Finder -> Applications -> Time Machine 1. Launch Time Machine 2. Slide the "yes-no" button to the "yes" 3. Click "Add a Backup Disk" then "Use Disk" 4. Your first backup begins, wait for it to be fully completed * * Your first backup can be long. We recommend that you run this first backup at night. If you have a portable Mac, do not forget to connect it to power. Once Time Machine is configured, backups are automatically performed every hour for the last 24 hours, every day for the previous month's data, and every week for data from previous months. When the backup disk is full, the oldest backups are deleted.