This article covers a lot of important points, but I must nitpick one in particular. GMT is not a timezone. Europe/London is a timezone. GMT is solar time which

This article covers a lot of important points, but I must nitpick one in particular. GMT is not a timezone. Europe/London is a timezone. GMT is solar time which is distinct from UTC as a time system. The purpose of leap seconds is to track the difference between TAI and GMT which results in UTC (i.e. UTC = TAI + leap seconds). Since everything is relative, my preference for recording accurate historical time is microseconds since TAI0. Everything else prior and future is an estimate.