Yesterday was my son's birthday. We were really busy all day long. In the midst of the shuffle, I needed to check something on the Mac. I was working for about three minutes and then the screen went blank. I tried to restart and it shut off as soon as it got to the login screen. Had I not made multiple backups last week, this would have been a much more stressful time for me. Instead of enjoying my son's birthday party, I would have been stressed about losing 2 years worth of photos. I want to run down 3 types of backups that you can do on your Mac. I recommend doing all three of them, but one is better than nothing. If you think I am crazy, just imagine losing photo you own.
Time Machine is the Mac's built-in backup and recovery tool. All you have to do is plug in an external hard drive and Time Machine will ask you if you want to use it for backup. As long as the drive is connected, it will back up all of your changes on the hour. If you disconnect and reconnect, it will catch itself up.
Benefits: It's built into the Mac and its easy to use. It's also an effective way to restore your data to a new Mac.
Negatives: There no off-site backup support (someone could steal it or or if your house was destroy in a fire).
Carbon Copy Cloner/SuperDuper!
Both of these programs are meant for cloning your disk to an external drive. The benefit of this is that this drive is actually bootable. You can either work off of this drive as temporary measure or simply put this hard drive in your Mac. I have mine set to make a clone every day at 4:00 AM.
Benefits: Cloning a drive is the fastest way to recovery from a damaged hard drive. You can boot from the clone and then using the cloning application to mirror the data to the new drive.
Negatives: Cloning programs are more complicated than Time Machine and it doesn't offer an offsite backup option.
There are multiple services that offer this. Crashplan, Carbonite, and Backblaze are some of the most popular. These involve paying a yearly fee (under $60) and installing a backup application your Mac. This application simply backs up your data to an offsite location (what the yearly fee is for).
Benefits: The backups are offsite.
Negatives: This option has the slowest recovery time. You would have to reinstall the OS and then download your data.