Timezone

When handling timezone always should have in mind these terms:

GMT = Greenwich mean time = Solar Time

UTC = Coordinated Universal Time = Atomic Time

DST = Day light saving time

CEST = Central Europian Summer Time

CET = Central Europian Time

So to make a software that handle well timezones follow these steps:

1. - Save date time always in UTC +00

2. - Display user timezone like GMT (+2 Europe/Rome)

3. - Use UTC expressions for technical talking and GMT expressions for general day to day talking.

At the end in case of timezone Europe/Rome you should know:

UTC = GMT (UTC + 0 hours)

CEST = (CET +1 hour) due to (DST +1 hour)

GMT (+2 Europe/Rome) = (CET +1 hour) due to (DST +1 hour) 

GTM (+2 Europe/Rome) = CEST

GTM +2 = CEST

Thank you.