With most of my correspondence, financial information, photos, etc. only existing electronically, it has always been important to have reliable and redundant backups. I’m sure you’re the same way, right? If something happened to your laptop or tablet or phone, you’d have a means of recovery, I’m sure (?).
I have archives of documents going back to at least 1994, and that is not because I've never had a crash. I’ve had numerous failures of hard disks (and even an SSD failure three years ago) which resulted in total data loss. With a backup system in place, however, I was able to recover virtually everything each time.
A caveat: my system is a bit complex and almost certainly unnecessary for most purposes. I will have a simpler recommendation at the end.
My primary computer is a MacBook Pro, so nearly all of the software I write about here is Mac-only.
My first and primary backup utilizes software which is already on your Mac: Time Machine. Time Machine isn’t perfect, and under the covers it’s actually a little bit gross, but it just works and you should be using it.
While my machine is at my desk, it is always plugged into an external Time Machine drive (a second external Time Machine drive also exists and I rotate between these two; one typically goes with me when I travel.) I use full disk encryption should I ever misplace one of my drives. If you don't have an external hard drive already,
this one is a fine choice.
When I am on my home network, I also utilize storage from a Synology Diskstation, a network-attached storage device. My Synology has five hard disks installed (two of which are RAID-6 redundant.) My Diskstation is connected to a UPS (Uninterruptible Power Supply) and serves out movies, TV shows, and large amounts of storage to our home network. A lot of stuff gets archived here. Among its many tasks though, it serves as a network Time Machine for all of the Macs in our house (currently three laptops.) My wife and teenager are backing up their computers and they don’t even know it (or care.)
Update 2017-03-08: I have migrated my Synology to the Btrfs file system. Among new features like checksums, auto-healing, and copy-on-write, Btrfs supports Snapshots. Snapshots, in computer storage terminology, is capturing the state of the file system at a particular point in time. This is more efficient than a full, file-for-file backup of the entire NAS. With snapshots, I can capture just the bits which have been changed since the last snapshot, later even rolling them back in time to a previous snapshot state. It's not a replacement for full backups, but it's a very handy tool to have.
So that takes care of my incremental backups. I also create bootable full-images of my Mac. To do this, I employ a second piece of software called SuperDuper. This, combined with a third external hard disk, allows me to restore everything very quickly to a bootable state in the case of catastrophic failure. Historically, I would have a second (encrypted) SuperDuper backup disk that I store off-site somewhere, but this has been harder to pull off since I started working from home.
Remote and Off-site
Okay, but what if my house burns down? Well, I’ve got that covered.
My Mac, starting each morning at 2:00 a.m., wakes up and sends an incremental backup of everything to Google Cloud Storage. To accomplish this I use a piece of software called Arq. Arq is a pretty powerful tool, which can send your data to just about anywhere. I chose Google Cloud Storage as the endpoint because it’s almost as inexpensive as competing Amazon Glacier, with much faster transfer speeds.
My Synology also has a remote backup. Once a week, the system sends an incremental backup of everything (currently 3.52 terabytes, plus another terabyte of Time Machine backups) to Microsoft Azure storage. Restoring all of that data after a catastrophe would take a few days, but at least it’s possible.
Remote storage does cost money, but it’s worth the small expense for peace of mind. My monthly storage and transfer fees for Google and Microsoft are about $30.
Assuming you have a Mac and are in the Apple ecosystem, you have no excuse not to buy an external hard drive and use Time Machine. Even if you only perform weekly backups, that’s better than nothing. I also recommend buying additional iCloud storage and keeping your photos there (with room to spare for your nightly iPhone and iPad backups). Honestly, backing up is not hard to do and it will save you a lot of heartache.
You can start adding some of my crazy redundancies (Arq or SuperDuper) as you deem necessary for your storage needs. The important thing is just to start backing up, even if only with the simple Time Machine. Do it now.