Amendments during autumn and spring do 78 countries to. In Latvia summer and winter time was introduced in 1981, and since 1997 the switches is done on the last Sunday of March and last Sunday in October.

The use of the system summer and normal time is one and constant in the EU countries. In all member countries of the European Union being translated in the same day, with the same stroke of the clock — in accordance with the position relative to the zero Meridian, or in accordance with customary international time.

For the first time the transfer of the clock forward an hour in summer and back an hour in winter to save energy resources was held in Britain in 1908.