1. What is a "Backup" and how important is it that I be Backed up?
A backup is an exact copy of your data on a different media storage device other than your built-in hard disk drive (HDD) or solid state drive (SSD). That usually means and external hard drive or for small amounts of data, a flash or thumb drive. The importance of being backed up depends on what information you have stored on your computer. Pictures? Music? Documents, like that novel you have been working on for years or school work? If you can't or don't want to retake the pictures, re-download the music, retype all the documents or school work, then you don't need to be backed up. If it is important, BACKUP. Every week several people come in to Century 23 with a problem computer and their data is extremely important and they have no backup. Most of the time (about 80%), we can recover the data. It usually costs about $200 to $300 if we can recover it. If we can't, then we can send your hard drive to a special facility than can recover the data that we can't. It is quite expensive and usually costs between $1,100 and $3,500. HOWEVER, they can't always recover your data. Sometimes the information is just destroyed and can't be recovered.
Remember, a backup is a second copy of your data, not the only copy that happens to be on a hard drive named "Backup". Most backup drives are larger than the internal drive. When the internal drive starts to fill up, the temptation is to delete files to make more room because, "they are also on my backup drive should I need them". They may be there but they are NOT backed up any longer. Your backup drive will also, someday, fail. Backed up means, at least 2 copies of the data. I am a bit of a backup freak (can you tell?) and I have 3 identical back up drives of my important data, one of which I keep at a different location than next to my computer (fire, burglary or earthquake).
2. Any thing I should know about operating system upgrades like updating to Mavericks?
Before performing any update to the operating system (OS) software I always make sure I have a complete backup. I prefer a bootable backup that I test by rebooting my computer from the backup, then I reboot to my regular start up disk, then I update. Recently, when I upgraded my laptop to Mavericks, my hard drive failed and I had to replace it with a new one (thank goodness for AppleCare!). I would have lost all my information had I not had a good backup. Also, check if your have the recommended RAM memory or hard drive space. Application programs you currently have may not work with the new OS. Check before you upgrade, downgrading can be a huge pain.