The second was once 1/86,400 of a day. Now it's defined by caesium atom oscillations — 9,192,631,770 per second — because GPS requires nanosecond timing to achieve metre-level accuracy. Here's the history from sundials to atomic clocks, how GPS trilateration works, and why relativistic corrections are essential.
Nanoseconds define CPU cache speeds; milliseconds define user experience; microseconds determine whether distributed database clocks can be trusted. Here's the computing time hierarchy, NTP clock synchronisation, why leap seconds cause outages, and what P99 latency means.
Learn time unit conversions across scales — from nanoseconds in computing to centuries in history — how many seconds in a year, what 10,000 hours really means, and how to convert any duration with a free time converter.
Learn how time units from milliseconds to years relate to each other, with real examples from computing, project planning, physics, and finance — plus a free time unit converter.
