Notes as of 12/17/2019, comparison info in table compiled by smi.
I'm always looking to add more storage options, comments on any of these, and help expanding this info

• Back up files off-site
• Access files from multiple devices (all of your PCs, Macs, phones, tablets)
• Share files with trusted humans (e.g., spouse, heirs)

• Disk space stored on the Internet and accessed via your connection to the Internet
• Provided by several companies
• Usually some space is offered for free and if you need more space there is a cost
• The space (and its files) are protected by your login credentials
• Some providers offer file encryption

details - enterprise storage forum

• Passwords. Can be hacked; so choose a password hard to hack with dictionary attacks, change it often to reduce exposure to brute force attacks
• Data can be captured en-route.
  • Most storage services encrypt data while it's traveling back and forth
  • Look for “https” in the browser, means “secure http”
• Don't give your password to anyone
  • Except your heirs
  • Not someone claiming to be from technical support, real tech support won't need password
• Most hackers want best bang-for-the-buck; so use provider with good history of keeping data secure
• Your data is not immune to search and seizure by local government entities (e.g., subpoena)

• Consider what you plan to store and how you need to access it
• Consider how important it is to keep that information secure (medical history & home finances vs music files)
• Safety features
  • Company with reputation for physical and network security
  • Multiple level redundancy (multiple copies of data prevent SPOF)
  • Redundancy across geographic locations (multiple locations prevent SPOF from nature)

details - how stuff works
SPOF: Single Point of Failure

• Use hardcore passwords
  • KISS is bad, complex is good (KICS?)
  • Consider using a password manager to generate and store complex passwords. Which will be safer and harder to guess: cgKZdxUhh4Bq (entropy 66.79) or Th1$C0mpu73rGr0up (entropy 24.17)
  • Use unique passwords for data in the cloud
  • Consider storing the first part of the password in a password manager and adding a set string when you enter it.
• Use two factor authentication if possible
• Backup files in different cloud accounts (don't put important data in just one place)
  • Best if you can store files offline as well as online/cloud (immediately puts data in two places)
• Practice smart browsing (if you're accessing the cloud – files, email, etc – remember to log out and never save password to browser)

details - malwarebytes

Also see these sites, they may have bargains:

• Tech Radar has really good info and compares prices for dozens of sites
• Tom's guide

Here are some, do you know of others?
Do you have good or bad experiences with these?

2FA: Two Factor Authentication, id and password and code texted to phone.
reference 1

• How to Get 100GB of Free Google Drive Space on a Chromebook – note it's just for 12 months. Also there are other offers, e.g., Disney+ Duet Display, more