A wall clock is an important and central feature in most homes. They provide great value by helping keep tabs on our schedules and obligations, and can provide a beautiful focal piece for a room’s design aesthetic.

The common design for a clock is the classic white circle separated into twelve equal-sized wedges. The lines delimiting each wedge are marked with a simple line or a numeral representing the twelve hours that make up the morning (A. M. Hours) and the twelve hours of the evening (P. M. Hours). Two arms on the clock rotate through those hour marks. The short arm represents the hour, and the long arm represents the minutes. (Calculating the minutes requires multiplying the number marked by the arm by 5. For example, when the long arm is on the 3, the time is fifteen minutes after the hour.) Arms’ motion gives rise to the colloquial term “clockwise”.

In technical parlance, the device that most of us are used to - if it simply keeps time, but doesn’t make any noises - is a “timepiece”. A “clock” is the timekeeping device that makes a noise to mark the hours and various increments thereof. These clocks might play a song, a simple chime, or gong or bell. (When a bell or gong is involved, the device is called a “striking clock”.) The common forms of these noise-making devices are the German cuckoo clock, or the large-scale grandfather clock.

Historically, the current mechanical, digital, and electrified timepieces came after the original sundials and water clocks. The newer clocks address technical shortcomings. (Sundials operate based on a shadow, which is problematic when the sun is down. Water clocks operate by transferring fluid between vessels, but the water evaporates.)

Across the world, among the most famous landmarks are clocks of all shapes and sizes. The biggest one is in Yokohama, Japan, and is called the Cosmo Clock 21 - it’s on a ferris wheel. Probably best known worldwide is the Big Ben clock tower at Westminster in London, England. The Doomsday Clock is a famous symbolic clock showing humanity’s likelihood of causing a worldwide disaster, like a nuclear war. It was created by the board of directors for the Bulletin of Atomic Scientists.

Similarly, often communities will install a large timepiece as a center of pride. For example, San Francisco has an iconic tower on the Ferry Building where the Embarcadero and Market Street intersect. Major universities have also built clocks as a part of their physical plant. At the University of California, Berkeley, Sather Tower was built at the center of the campus (styled to look like the Piazza San Marco - it’s even nicknamed the Campanile).

Picking the right wall clock for your home or office is an important choice. Each timepiece displays the time in a different way, so choosing one can be deeply personal but also a lot of fun.