Summer time is upon us
At 0100 GMT on 28 March, clocks in Europe moved forward by an hour as civil time moved to summer time.
In UK, the move was from Coordinated Universal Time (UTC) Time - almost identical to Greenwich Mean Time - to British Summer Time (BST).
The European Parliament and Council Directive on Summer Time Arrangements states that summer (or daylight saving) time will be kept between the last Sunday in March and the last Sunday in October. The changes will take place at 0100 GMT - so European clocks will move back at 0200 BST on 31 October.
Many countries around the world use daylight saving time, but not necessarily between the same dates as in Europe - see Time & Date below.
International transport will still be based on UTC or 'Zulu' time, representing the 15º of longitude centred on the Greenwich meridian. But UK local time will be 'Alpha', centred on 15ºE. See World Time Zones below.
Each year, some people advocate that summer time be kept all year round - but this is opposed by others, especially in the north.
For an interesting history on daylight saving time, see the National Maritime Museum link below.