zoneinfo

Zoneinfo refers to a collection of time zone definitions and rules used by computer systems to convert times between time zones and to compute local times for a given timestamp. It is based on the IANA Time Zone Database (tzdb), which records historical and current offsets, daylight saving time (DST) transitions, and policy changes for regions worldwide. Zoneinfo data is organized as a set of named zones, typically with names in the form Continent/City, such as Europe/London or America/New_York. Each zone file contains a sequence of transitions with effective timestamps and the corresponding UTC offsets, as well as information on DST.

In Unix-like operating systems, the zoneinfo database is stored in a directory like /usr/share/zoneinfo and is used by system libraries and applications to resolve a zone name to a precise offset for a given instant. The IANA tzdb is maintained by IANA with contributions from many organizations and individuals; updates are released periodically to reflect legal changes, new zones, and DST adjustments.

In programming, the term zoneinfo appears in multiple contexts. For example, Python includes a zoneinfo module (introduced in Python 3.9) that provides access to the IANA database; it can use the system tzdata or a bundled copy. Other languages use embedded or external tzdata to perform similar lookups.

Despite differences in implementation, the core purpose of zoneinfo remains consistent: provide accurate, up-to-date time zone information to enable correct time computations across regions and over time.