BigCityBoy
You just look outside or base it upon when you woke up
Ottoman
I knock on my next-door Nabours door and ask them if it's day or night.
Anonymous
NO THEY DO NOT BUT EVERYONE KNOWS BY DAYLIGHT..
Kathy
Wall clocks in my home do not specify either one. I just know which one it it.
David S
Analog clocks usually have 12 hours, but it's easy to know whether you're in AM or PM due to our daily schedules.