Epoch

When is Epoch ?

• In Christianity, the epoch of the anno Domini calendar era is the Incarnation of Jesus.
• North Korea uses a system that starts in 1912 (= Juche 1), the year of the birth of their founder Kim Il-Sung.
• iOS 1 January 2001 

Religion and fanaticism aside:

• UNIX epoch: 1 January 1970 
• Internet epoch(NTP): 01 January 1900
• DOS epoch: 01 January 1980 (Because fudge you, that's why) 

Why is this relevant?

Epoch is commonly used in APIs/service communication.

If you don't know what epoch you are getting/sending there is a good chance the software won't work properly.