What is UTC or Universal Time Coordinated?

There’s our own community’s local time and then there is standard time, known today as Universal Time Coordinated or UTC. (It used to be called Greenwich Mean Time or GMT). UTC is expressed as a 24 hour clock (so I PM is 13.00 hrs.) and is based on careful measurements of the Earth's rotation. UTC never changes for daylight savings time as many local time zones do. Instead, it continues on unaltered. UTC is maintained by the Bureau International des Poids et Mesures (BIPM). UTC time is also known as "Z time" or "Zulu Time". What time is it UTC ?