Quite simply it’s when we change the clocks to go forward for one hour on the final Sunday in March to signify British Summer Time and back one hour at the end of October.
The clocks going on one hour in March enables us to have more daylight in the evening.
It all started at the beginning of the 20th Century with a proposal from a British builder named William Willett, who happens to be the great-great-grandfather of Cold play’s Chris Martin.
The National History of Science at the Royal Observatory Greenwich stated that Mr Willett was incensed at the waste of daylight during the months of Spring and Summer.
As he was riding his horse through the Chislehurst and Petts Woods he was aware that many people were sleeping on even though the sun had been up for hours.
In 1916, British Summer Time was adopted to enable us to save fuel and money and get out in the sunshine for longer to improve our health.
Britain has thought of moving the clocks a number of times, even to the extent of forwarding the clocks by two hours ahead of GMT during the Second World War.
They have also been periods when the clocks were brought forward in the spring of 1947, which was to help with fuel shortages.
Britain even tried to experiment with keeping the clocks one hour ahead of GMT throughout the years of 1968 and 1971.
But they reverted back to our system of winter and summer times in March and October.
The ideas for clock-changing were first noted by Benjamin Franklin, one of the founding fathers of the US, in 1784.
He wanted to try and save candle usage and get people out and about to benefit from natural sunlight.
Then in 1895, over 100 years later, George Vernon Hudson a New Zealand entomologist suggested clocks be put forward two hours in the summer.
So the primary reason we use Daylight Saving Time is that people can simply enjoy long summer evenings in natural light, better for your health and energy conservation.
In 2019, the Daylight saving time (DST) in the United Kingdom began at 01:00 on Sunday, 31 March and ends at 02:00 on Sunday, 27 October.
In 2020, there will be a change of dates, as is the case every year, when the Daylight saving time in United Kingdom will begin at 01:00 on Sunday, 29 March and ends at 02:00 on Sunday, 25 October.
All of the quoted times for DST are in United Kingdom Time.