Every major IANA time zone: its standard UTC offset, and whether daylight saving still applies there.
Software should store time zones by their IANA names, America/New_York, Asia/Kolkata, never by raw offsets, because the name carries the rules: when DST starts, when it ends, and the history of every change the government has made. This directory lists the zones covering the overwhelming majority of the world's population with their standard (winter) UTC offset and current DST status, which is the table you need when configuring a server, a cron job, a calendar integration or a database.
The interesting rows are the exceptions, and they are flagged honestly: Arizona (no DST inside a DST-observing country), Nepal's UTC+5:45 and the Chatham Islands' +12:45 (the world's odd-minute offsets), Mexico City and Sao Paulo (DST abolished recently, older tables still show it), Istanbul and Moscow (fixed offsets chosen by decree), and Kazakhstan (unified to a single zone in 2024). Offsets shown are standard time; add an hour where DST is in force. Governments keep editing these rules, the IANA database (tzdata) is the living authority this summary follows.
Why use a city name instead of 'UTC-5'? Because 'UTC-5' is wrong half the year for New York and permanently wrong for Bogota, which shares the offset but has no DST. The city-based zone name encodes the rules; the offset is just today's answer.
What does 'standard offset' mean for London? UTC+0 in winter (GMT) and UTC+1 in summer (BST). The directory lists the winter/standard value and marks DST as observed.
My zone is not listed, where is the full list? The full IANA database has ~600 zones including historical and alias entries. Operating systems expose all of them (timedatectl list-timezones on Linux); this directory is the working subset, not the archive.