UTC offset
The UTC offset (offset from Coordinated Universal Time) is the difference in hours and minutes from Coordinated Universal Time (UTC) for a particular time. For example, the local time in a time zone which observes UTC+8 is calculated by adding 8 hours to UTC.
Daylight saving time
Several regions in North America, Europe and Australia use daylight saving time (DST). The UTC offset during observation of DST is typically obtained by adding one hour to standard time. Central European Time UTC+01:00 becomes Central European Summer Time UTC+02:00, and Pacific Standard Time UTC−08:00 becomes Pacific Daylight Time UTC−07:00.