Mac folks… on every modern mac you have an amazing backup system that ships with Mac OS.
If you have not set up Time machine on your mac- DO IT RIGHT NOW.
There is ZERO reason to ever lose files on a mac with this system sitting right there for free on your machine.
I have seen several cases this week alone of folks losing data and don’t have time machine set up.
Help us help you by setting this up right now.
You can get a 2tb external drive for under $70 just about anywhere.
A much better alternative is backing up to a sparsebundle disk image on an external drive in regular intervals, at least 3 times a week. There are many good application that can automate your backups for you, like for instance SuperDuper! or Carbon Copy Cloner. Peoply that know there way around the Unix terminal can even do this with rsync.
If you ever lose data you can simply open the disk image and recover the files in question from your latest backup, or if your entire system installation gets corrupted (or your computer stolen), you can simply reinstate the entire system by booting to the recovery partition, and in Disk Utility restoring your main hard-drive partition from the latest backup disk image.
Why is this better? Well doing a full recovery from a Time Machine pseudo-backup can take more than 10 hours, whereas simply copying files from a disk image to a local hard-drive will take at best an hour or two for most users.