Why your computer forgets unsaved work when the power dies

Your computer has two kinds of memory. Storage (the SSD or hard drive) is a big filing cabinet that keeps files with the power off. RAM is a small, very fast desk that holds whatever is open right now, and forgets it all the instant power stops.

Opening a file copies it from storage into RAM; saving copies it back. That's why a power cut leaves you with the last saved version. Try a desk-and-cabinet simulator with a pull-the-plug button, and see how much slower storage really is when one RAM access takes a second.