The first letter of DST stands for "Daylight". In the world before time zones people basically used three references based on sun position, sun rise, sun set an

The first letter of DST stands for "Daylight". In the world before time zones people basically used three references based on sun position, sun rise, sun set and noon. The introduction of time zones decoupled noon from the time when the sun was at the highest and was part of the process that led to people doing things by the clock and not the sun. Because sun rise and set vary with respect to time zone time DST was an attempt to partially allow people to just start doing things when the sun came up.