For many years I backed up my files by creating copies on other disks or other drives. I only did this when I remembered.
This is still the method many people use.
Over ten years ago I went to a presentation by a woman who was speaking about data, electronic files, backups, and so on. She said that she had talked to multiple parents and grandparents who had lost many early pictures of their children because the pictures were on a cell phone, and nowhere else. The cell phone died, and so did the pictures.
I broke out of my own bad habits after reading comments about businesses destroyed by computer crashes. That finally made me appreciate the difference between time and money. The money to buy a replacement computer probably can be found. The time to recreate all the lost files probably cannot be found.
I did install a program which regularly backs up my computer files, some time last year.
There are multiple ways of creating file backups. Currently I’m using Macrium Reflect which creates a disk image. I can also use a program which will only back up certain files and directories I choose. Maximum PC magazine had a recent article listing various useful programs for Windows, including a backup program. I will start going through that list and seeing what I like and what I don’t.
(That decade-ago lecturer also said if you really want to save photos for posterity, print them out. Nothing digital will be as reliable. I believe that, yet that is something I haven’t yet done myself. That will be a project for late this year or early next year, to start picking which photos I want printed and looking into how to get them printed.)