I learnt the reason for changing the clock backwards or forward is due to changes in summer and winter or the length of day and length of time.

I hope it's not a daft question. But I seriously need a detailed explanation to the understanding of a lay man.

If time can be changed manually due to some meteorological reasons I wish to understand better, doesn't that mean it can also be manipulated for selfish or I'll rather say political reasons?

Please, I would be extremely grateful if anyone can explain to my understanding the reason for clock changes or time zone change in European countries.

I'm more interested in that of France though. But I'm sure the explanations related to other countries will suffice.

European Summer Time is the variation of standard clock time that is applied in most European countries, not including Iceland, Belarus, Turkey and Russia — in the period between spring and autumn, during which clocks are advanced by one hour from the time observed in the rest of the year, in order to make the most efficient use of seasonal daylight. It corresponds to the notion and practice of "daylight saving time" to be found in many other parts of the world.

https://en.m.wikipedia.org/wiki/Summer_Time_in_Europe

27 Mar 2016 - Daylight Saving Time Started
When local standard time was about to reach
Sunday, 27 March 2016, 02:00:00 clocks were turned forward 1 hour to
Sunday, 27 March 2016, 03:00:00 local daylight time instead
Sunrise and sunset was about 1 hour later on 27 Mar 2016 than the day before.

https://www.timeanddate.com/time/change/france?year=2016

On October 30, 2016 at 3 in the morning the clocks are changed back from Winter Time to Daylight Savings Time in France. The clocks have to be shifted from 3 to 2 am. So, the people can enjoy this very hour twice. The winter time, also called normal or standard time, is going to be valid until the next Time Change to daylight savings time in the upcoming year

http://www.timechange.info/france-2016/



I'm still in need of some explanations