CET is 1 hour ahead of Coordinated Universal Time (UTC). During the summer period most Western European countries change the clock 1 hour so that we run 2 hours ahead on UTC. It’s called “Summertime” or Daylight Saving time (DST).
The change of winter and summer time has been under discussion for years. In recent years, this discussion has been increasingly conducted on European level. The European Parliament has voted to abolish clock movements by 2021. However, it is difficult to get all member states to vote the same, which makes it doubtful whether this will actually happen.
Many countries, just like the Netherlands, use the 24-hour format. While mostly English-speaking countries are used to the 12-hour format (AM / PM) in which the day is divided into two half-days.