There are quite a few symbols that are hardly used anymore in real life, yet are still going strong as icons.

Take the telephone icon, for example! When building a website, it's not unusual to use a rotary-dial telephone icon for "Contact us by phone." In terms of actual usage, smartphones are overwhelmingly dominant, but even people from generations who have never used a rotary phone still recognize the symbol as meaning "telephone."

Likewise, the icon for saving in computer software is a floppy disk. Even though hardly anyone uses them anymore—and some people have never even seen one—plenty of software still uses this icon.

With design, keeping up with trends matters, but separately from that, there are times when being understood by as many people as possible is also required. Innovative designs look fresh and cool, but if they're too new, a lot of people simply can't keep up.

And icons and symbols often have to convey their meaning with a simple design within a limited space. In the case of the telephone icon, if you took the increase in smartphone users into account and designed it as a smartphone-like rectangle, it would end up resembling the sheet-of-paper icon for creating a new file, and since smartphones are used for browsing the web as well as making calls, it would only cause confusion.

With the 2020 Olympics in mind, various symbols are being reconsidered, from the debate over the hot spring logo to restroom icons. We'll likely have more chances to see new symbols, so it might be interesting to pay attention to them.