When do you use a floppy disk?

Answer 1

Rarely because they are considered obsolete. No computer built today includes a floppy disk drive or controller. You would have to buy an external one that could be connected to your computer by USB to be able to use a floppy disk (and these are getting harder and harder to find).

Answer 2

Nowadays, not at all. I have a USB floppy drive I purchased for the business about 11 years ago and the last time I used it for any project was probably six or seven years ago. They are not utilized anymore as the storage capacity of a floppy disk is infinitesimally small by today's standard (a high-density floppy could store up to 1,457,664 bytes, about 1.4 megabytes) and the file access speed was atrociously slow.

In the modern day, people use flash drives, CD-RW discs, or other means to port files from one computer to another if they wish to do so by the old "sneakernet" method. (Sneakernet was the jovial term given to sharing files between computers by carrying them on some sort of floppy, flash drive, etc. and walking in your sneakers to get them to the destination machine.)