Clockmakers developed their art in various ways. Building smaller clocks was a technical challenge, as was improving accuracy and reliability. Clocks could be impressive showpieces to demonstrate skilled craftsmanship, or less expensive, mass-produced items for domestic use. The escapement in particular was an important factor affecting the clock's accuracy, so many different mechanisms were tried.
Early clock dials did not indicate minutes and seconds. A clock with a dial indicating minutes was illustrated in a 1475 manuscript by Paulus Almanus, and some 15th-century clocks in Germany indicated minutes and seconds. An early record of a seconds hand on a clock dates back to about 1560 on a clock now in the Fremersdorf collection.:417–418
Howard Miller 625-323 Alton wall clock. Matte black case with shatter-resistant acrylic crystal. White dial and large, easy-to-read black Arabic numerals. Auto Daylight-Savings movement automatically adjusts for Daylight Savings Time. The hands of the clock follow an LCD display on the back of the clock and make corrections to keep the correct time including Daylight Saving Time corrections.
Water clocks, also known as clepsydrae (sg: clepsydra), along with the sundials, are possibly the oldest time-measuring instruments, with the only exceptions being the vertical gnomon and the day counting tally stick. Given their great antiquity, where and when they first existed is not known and perhaps unknowable. The bowl-shaped outflow is the simplest form of a water clock and is known to have existed in Babylon and in Egypt around the 16th century BC. Other regions of the world, including India and China, also have early evidence of water clocks, but the earliest dates are less certain. Some authors, however, write about water clocks appearing as early as 4000 BC in these regions of the world.
“Love how simple this digital timer is. I travel a lot, and it’s small enough to put in my purse. The off button is convenient because it keeps the buttons from being pressed while stored away and conserves the battery, but when you turn it back on, your setting are stored so no need to reset [each] time. … [There’s just the] clock, alarm, snooze, on/off. The smaller and simpler the better when I’m traveling.”
The word horologia (from the Greek ὥρα, hour, and λέγειν, to tell) was used to describe early mechanical clocks, but the use of this word (still used in several Romance languages)  for all timekeepers conceals the true nature of the mechanisms. For example, there is a record that in 1176 Sens Cathedral installed a ‘horologe’ but the mechanism used is unknown. According to Jocelin of Brakelond, in 1198 during a fire at the abbey of St Edmundsbury (now Bury St Edmunds), the monks 'ran to the clock' to fetch water, indicating that their water clock had a reservoir large enough to help extinguish the occasional fire. The word clock (from the Celtic words clocca and clogan, both meaning "bell"), which gradually supersedes "horologe", suggests that it was the sound of bells which also characterized the prototype mechanical clocks that appeared during the 13th century in Europe.
Simple clocks intended mainly for notification were installed in towers, and did not always require faces or hands. They would have announced the canonical hours or intervals between set times of prayer. Canonical hours varied in length as the times of sunrise and sunset shifted. The more sophisticated astronomical clocks would have had moving dials or hands, and would have shown the time in various time systems, including Italian hours, canonical hours, and time as measured by astronomers at the time. Both styles of clock started acquiring extravagant features such as automata.
“I am the heaviest sleeper and was setting four or five alarms on my phone to wake me up. After being late a few times, I decided to purchase this alarm clock to help me wake up on time. I couldn’t be happier with my purchase. … The bed shaker is super important. I put it under my pillow, and it shook me awake; the loud beep helped too. If you can sleep through earthquakes and shouting family members, this is the alarm clock for you.”