This applies mostly to those who have an USB external hard drive that is used for periodical backups of your data. I myself use that method for my daily computer data backups. However, I only plug it in at the time of the backup and otherwise keep it disconnected from my computer. Why, you might wonder?
1. In power surge prone areas, if one hits your computer, and your external hard drive is connected to it, and it’s powerful enough, it will fry your computer AND your external hard drive.
2. There are malware infections that will encrypt your files and then ask you for a ransom to decrypt them (aptly named ransomware). The recent versions of it will encrypt files in any drive connected to your computer, not just your internal hard drive. So your only hope for recovery from such infection would be thwarted since the backup data in your backup drive will also be encrypted.
So know your backup schedule, and do what I do, put a reminder in your calendar so it reminds you a few minutes before your scheduled backup, and only then connect your external hard drive to your computer. And unplug it from your computer (and from any power source if it has its own power adapter) when done. Doing this might save the day if disaster strikes.
And if you don’t have a backup plan in place for your computer data, well, I suggest you get going on that. Don’t say I didn’t warn you. 🙂