A lot of people don't know that the time-zones of all countries are advanced one hour during summer time.
If you were in the time-zone GMT+0 during Winter, you are now in GMT+1. For example the current time in Britain (usually GMT) is not GMT+0, but rather GMT+1 now. UTC-time-zones are also advanced one hour. There are tow options to list time now: in GMT+0 or in GMT+1. With the first option, everyone has to know that he or she has to adds one additional hour to the hour he usually adds or detracts to get his local time. With the second option everyone can stick to the previously number of added or detracted hours, ie. someone from England wouldn't have to add any hours to a GMT#1 time, while Germans would have to add the usual one hour they'd also have in Winter with GMT+1.
As graphics can describe it maybe a bit better (I only have a European map, other continents can however still find their time in the links):
Blue=GMT+1 | Red=GMT+2 | Yellow=GMT+3 | Green=GMT+4
http://en.wikipedia.org/wiki/Western_European_Summer_Time
http://everytimezone.com/
http://tghq.org/tghq/timezones.php
http://wwp.greenwichmeantime.com/
If you were in the time-zone GMT+0 during Winter, you are now in GMT+1. For example the current time in Britain (usually GMT) is not GMT+0, but rather GMT+1 now. UTC-time-zones are also advanced one hour. There are tow options to list time now: in GMT+0 or in GMT+1. With the first option, everyone has to know that he or she has to adds one additional hour to the hour he usually adds or detracts to get his local time. With the second option everyone can stick to the previously number of added or detracted hours, ie. someone from England wouldn't have to add any hours to a GMT#1 time, while Germans would have to add the usual one hour they'd also have in Winter with GMT+1.
As graphics can describe it maybe a bit better (I only have a European map, other continents can however still find their time in the links):
Blue=GMT+1 | Red=GMT+2 | Yellow=GMT+3 | Green=GMT+4
http://en.wikipedia.org/wiki/Western_European_Summer_Time
http://everytimezone.com/
http://tghq.org/tghq/timezones.php
http://wwp.greenwichmeantime.com/