Standard time zone boundaries are invisible in the landscape, yet they abruptly delineate a temporal difference of one hour between two large areas located relative to one another on Earth. In most cases, standard time zone boundaries follow political ones and define areas within which daylight saving time (DST)--the seasonal advancement of standard time by one hour--is observed. Moving time zone boundaries and the decision to observe daylight saving time occurs throughout the world for various reasons that result in the synchronization of socioeconomic and political activities within and between communities and the simultaneous separation from others.