UTC

I am not sure, but Windows seems to be the only operating system, that wants the computer clock to be set to the local time zone instead of universal standard time (UTC). Maybe that is a relic of the times when Microsoft thought that the internet was not very important for the future of computing. All other operating systems apparently use UTC: MacOS, Android, Linux, BSD, ... However, if you are dual-booting your computer, you can get into trouble. Not all operating systems detect automatically a dual boot install and adjust their behaviour in order to be compatible with Windows.

If I am not mistaken, Windows is the only OS, that uses local time for the system clock (instead of UTC). This means that in multiple boot configurations, every restart of the system into Windows will screw up the system time. In order to reset it (in Ubuntu 16.04), use
sudo timedatectl set-timezone Etc/UTC