I wish they would do away with that ! It's a pain to set all the clocks and I don't really see what the difference is anymore. Always takes a week or so to get used to the time change. If they dumped it? It sure wouldn't break my heart any.
The main purpose of Daylight Saving Time (called "Summer Time" in many places in the world) is to make better use of daylight. We change our clocks during the summer months to move an hour of daylight from the morning to the evening. Countries have different change dates.