- GMT The Korean local time is normally
GMT +09:00. GMT is an abbreviation for Greenwich Mean Time, which is the clock time at the Royal Observatory in Greenwich, U.K. located at longitude 0.
UTC Many consider GMT and UTC the same thing, and the two are used interchangeably in many cases, but they are actually different.
UTC+09:00means the local time is 9 hours ahead than the UTC standard time. This means that it’s 09:00 PM in Korea when it’s 12:00 PM in a UTC region.
Date object. It is a native object defined in ECMAScript, like
Function. which is mostly implemented in native code such as C++. Its API is well described in MDN Documents. It is greatly influenced by Java’s java.util.Date class. As a result, it inherits some undesirable traits, such as the characteristics of mutable data and
month beginning with 0.
You can find more interesting examples here.