Since Mac OS X Leopard, Apple provides Mac users a way to back up Mac with Time Machine, a software tool designed to work with the Time Capsule storage product, as well as other internal and external disk drives. Backing up your Mac with Time Machine is an important step to go, especially if you are planning to format hard drive on Mac, reinstall Mac and do other big changes to your Mac.
Time Machine backs up your entire Mac, including system files, applications, accounts, preferences, email messages, music, photos, movies, and documents. Follow the tutorial to learn how to back up Mac with Time Machine.
If you haven't specified a Time Machine backup device and you connect an external drive, Time Machine will display you the following dialog:
You can use the Time Machine menu in the Mac toolbar to verify the status of your backups. When Time Machine is backing up your data, the circle and the clock hands spin counter-clockwise. Click on this menu to see the time of the Latest Backup. The Back Up Now option allows you to back up Mac immediately.
For those who lost data on your Mac but forgot to back up MacBook Pro, MacBook Air or other Mac computer, the post How to Recover Lost Data on Mac Hard Drive might give you some insights.