Millions of people click a little floppy disk every day to save their work — many of whom have never held one. How did an obsolete storage device become one of the most recognised symbols in computing?

The disk itself

Floppy disks began in the early 1970s as 8-inch flexible magnetic disks, then shrank to 5¼ inches. In the early 1980s Sony introduced the 3.5-inch disk in a rigid plastic case with a sliding metal shutter — the square shape everyone now pictures. It typically held 1.44 MB, roughly one high-resolution photo today.

Why it became the save icon

In the 1980s and 1990s, “saving” literally meant writing your document to a floppy disk. Graphical programs of that era needed a small picture for the Save command, and a disk was the obvious choice: it showed exactly where your work was going.

Why it never changed

By the late 2000s floppy drives had disappeared from computers, replaced by hard drives, USB sticks and the cloud. But by then the icon had become the meaning of save, not a picture of a disk. Designers experimented with arrows and clouds, yet nothing is as instantly understood — so the floppy stays. Icons like this, which imitate an old physical object, are called skeuomorphs; the phone handset icon and the envelope for email are others.

More computing history: the history of undo, cut, copy and paste.