There are numerous options for online backup which is great as you can choose exactly the one that suits your needs. 

Only rule with backup is that you DO IT! 

I have heard too many times -"my computer crashed and I lost EVERYTHING!" Make sure that does not happen to you by signing up for online backup which does it automatically and then you always have backup off site (very important!).

I have tried below services and all come recommended, and am using one as my backup provider.

Secure. Offsite. And the only online backup service that doesn't need you to pick folders and filetypes. 
You download a tiny application that installs in three clicks and doesn't require a credit card or any information to start using it. This internet backup application automatically finds all your photos, music, documents, and other irreplaceable files—no matter where they are on your hard drive—and compresses and securely encrypts them. When you're not using your computer, it sends them over the Internet to the remote Backblaze datacenters.
Backblaze is so easy to use, that you won't even know it is there. You will love it.

When you install IDrive for the first time, a default selection of most commonly backed up data including Documents, Pictures and Videos is created with a random after hours schedule. You can customize the selection and schedule.

Create and manage multiple accounts from a single account, via the web. Login via any browser to your account to access backed up data, view log reports and restore data on the local system. Enhanced security with 128-bit SSL encryption on transfers, 256-bit AES encryption on storage with a user defined key that is not stored anywhere on IDrive servers. Plus many more.
Did you back it up? 

Go to iDrive.

KeepVault features real-time backup to safe and secure RAID6 online servers AND also, on Windows systems, simultaneous backup to a USB/SD/NAS drive. KeepVault combines the speed & convenience of local protection with the disaster-proof protection and accessibility of online backup!

Real-time Protection
Many other online backups have a serious flaw; their software only backs up when it feels like it. Ask yourself this, do you know when you're going to lose data? KeepVault protects files as soon as they change, reducing the chance of data loss to a minimum.

Your Data is Secure
KeepVault online backup encrypts data files on your computer BEFORE transmission to secure Tier3+ online backup servers (located in geographically safe Michigan USA). With KeepVault backup you choose the encryption key for maximum security.

Go to KeepVault.