When protecting your data meant punching a hole in it

"The presence of a notch made the floppy write-protected, so you started with a write-enabled floppy, and if you wanted to protect it, you punched a notch at just the right spot."

"The presence of a notch made the floppy write-enabled. To protect it, you covered the notch with a sticker. So it was really a write-enable notch, not a write-protect notch."

"The advent of the 3.5-inch floppy simplified things, introducing a sliding switch on the underside of the disk. An open hole meant the disk could be written, while closing the hole protected the disk."

Removable media write protection has undergone significant changes throughout computing history. Early eight-inch floppy disks used a notch at the top leading edge where presence indicated write protection. The 5.25-inch disk reversed this logic with a write-enable notch on the right edge that required a sticker to protect data. Users creatively modified disks with hole punches to create flippy disks for dual-sided use. The 3.5-inch floppy introduced a sliding switch mechanism on the underside, simplifying protection. Compact cassettes used breakable tabs at the top for protection, which could be temporarily restored with tape. Modern flash drives employ either physical write-protect switches or software settings for data security.

Read at Theregister