About UTC time
Coordinated Universal Time (UTC) is the global reference against which every other time zone is measured — the successor to Greenwich Mean Time.
UTC is maintained by a global network of atomic clocks and kept within a second of astronomical time using occasional leap seconds. Pilots, servers, and scientists use “Zulu time” (UTC) to avoid any ambiguity from local offsets or daylight saving. Every city page on this site derives its offset from UTC.
Global reference standardAviation & computing “Zulu” timeAtomic-clock based