Greenwich Mean Time

[shazzabell]

How did my computer 'know' to change to GMT?

[fo3nix]

It happens at the same time each year, so can easily be factored into the programming.

[rojash]

It will only happen if:

a) You have selected the correct time zone
b) You have checked "Automatically adjust my clock for daylight saving changes"

You can access these two options by double-clicking your clock, and selecting the "Time Zone" tab

[shazzabell]

Thanks!