Daylight Saving Time - Computing

Computing

Changes to DST rules cause problems in existing computer installations. For example, the 2007 change to DST rules in North America required many computer systems to be upgraded, with the greatest impact on email and calendaring programs; the upgrades consumed a significant effort by corporate information technologists.

Some applications standardize on UTC to avoid problems with clock shifts and time zone differences. Likewise, most modern operating systems internally handle and store all times as UTC and only convert to local time for display.

However, even if UTC is used internally, the systems still require information on time zones to correctly calculate local time where it is needed. Many systems in use today base their date/time calculations from data derived from the IANA time zone database.