Daylight savings time (which is called “summer time” in Britain) is the practice of setting clocks forward one hour during the months of the year when there is more daylight. When this is done, more of the daylight hours fall in the evening and fewer of them fall in the morning.
Daylight savings time was first introduced during World War I. At that time, the idea was that daylight savings time would make it so that people were awake more during the daylight hours. This would be helpful to the war effort because it would mean that people did not need to have artificial light for as much of the time that they were awake. This would allow them to use less coal for light, allowing that coal to be used for military purposes.
In recent years, daylight savings time has been expanded. The idea is that we will use less energy that way. There are many people who feel like this is pointless, however. People dislike having to change their clocks and get their bodies (and those of their children) to adjust to the different time.