Atomic Clock Time - Displayed in a variety of useful formats. Site is a front-end to U.S. government atomic clocks.
The Calendar - Summarizes the history of various calendars developed and used over the centuries.
Calendar Studies - Information about calendar history and calendar reform.
Calendar Zone - A categorized collection of calendar related sites.
English Calendar - Includes an ecclesiastical calendar and a section on old and new style dating.
A Few Facts Concerning GMT, UT, and the RGO - Explains the differences between several time systems.
Infoplease: Daylight Saving Time - Information and history about Daylight Saving Time all over the world.
International Standard Date and Time Notation - An overview of the ISO 8601 notation for dates.
Light of Day - Shedding light on Queensland's daylight saving opposition.
NIST Time and Frequency Division - The National Institute of Standards and Technology maintains time and frequency standards for the United States.
NPR : 'Seize the Daylight': A History of Clock Chaos - Benjamin Franklin first called for the government to tinker with clock hours in the 1780s. But it wasn't until World War I that the United States adopted daylight-saving time as a way to get more efficiency out of the day. "Seize the Daylight" Author David Prerau talks about the complicated politics and curious history of DST, and he shares an excerpt from his book. [4:54 streaming audio broadcast]
This Day In History - Today in history every day - often with pictures and sound.
Time - Provides descriptions of several standards of time.
Time FAQ - Frequently Asked Questions about time (from sci.astro news group)
Time References - To set your watch or clock accurately using a time reference. Explains the various options for residents of North America.
Time Zone and Daylight Saving Time Data - A directory of sites providing descriptions of civil timekeeping concepts, source code, databases, and maps.
Today's Calendar and Clock Page - Information on all things relating to calendars, dates, holidays, and time. Find today's date on several different cultural and religious calendars. Includes section on Celestial data, countdown clocks, and information on the dates past events.
United States Code - Weights, measures and standard time.
A Walk Through Time - Evolution of timekeeping through the centuries.
Clocks and Watches
Cesium Atomic Clocks - Kinds of cesium clocks, with pictures, plus a description of their operation and the science behind them.
Doug's Atomic Clocks - Details on Doug Hogarth's experiments with his atomic clock.
How Stuff Works: Atomic Clock - Concise history, background, definitions and operational information regarding atomic clocks.
How Stuff Works: Pendulum Clock - Concise description using drawings and animation to show the operation of a pendulum clock.
Smithsonian Institute - On Time - History of the clock and how Americans have measured time and been affected by it.
American Time Zones - Displays a map of the main parts of the United States, showing the time zones and the current local time. Time details for most US cities available.
ClockGenius - Shows the time in your preference areas of the world.
CNN - World Time - Time Zone Map with Shockwave graphics. Roll over time zones and get GMT offset, or roll over major cities, and get the current time. Swatch beat display and converter as well.
GMT - Provides comprehensive information on Greenwich and Time issues, including maps, GMT Converter and resources.
Human Clock - People in various situations holding signs of the time. Accepts photo submissions.
International Time Offset - A table showing time in relation to GMT, US Eastern, US Central, US Mountain, and US Pacific Time.
Local Times around the World - Database of countries, islands and regions, containing current time and related information.
Official U.S. Time - Public service cooperatively provided by the National Institute of Standards and Technology (NIST) and U. S. Naval Observatory (USNO). Clickable map of U.S.A. (Java Applet), gives the current time plus a world map showing current daylight.
People-Park Time Zones - Choose a world region and get a list with the current time ticking for each and every country in that region.
Time and Date - Current time in tables of places in the world. Can be sorted and otherwise customized. Includes meeting planner and other time-related tools.
The Time Now - Choose a country and get the accurate (US network of cesium clocks) synchronized time.
Time Zone Converter - Find the current time from a list of cities. Convert time between time zones (cities), or create a printable reference card with base reference and cities of your interest.
Time Zones Of The World - Live analog clocks provide fast local timechecks for 30 worldwide timezones. Based on PC program CLOX 2000.
Timeticker - GMT offset via Flash rollover world map. Lists all countries in the world, and returns ticking accurate current time.
TravelShop World Clock - Look up the local time in more than 200 countries. You can download and put this world clock on your homepage.
United States Time Zones - Provides current local time and a quick loading time zone map of the entire United States.
UTC - Current time UTC and current moon phase. Internal link to UTC definition and origin.
WeatherHub World Time - Displays local times in a selection of locations around the world, or selected world regions.
What Time? - Minimalistic converter.
What Time is It - Gives the current time, synchronized by NIST. Close to 100 different time zones supported, as well as the ability to select the default time zone.
World Buddy - Database containing weather information and current time in all areas of the world. Displays a sunlit globe image with the selected area indicated.
World Map Clock - Full world overview of current local time, 2 days of week plus day and night. Print version can work as slideruler.
World Time - Interactive globe image that can be centered with a click or by choosing a country. Current time for the map center will show as offset from UTC. Settings like zoom factor, color and state borders can be customized.
World Time Server - Look up current time from database containing any country or major city in the world. Displays the time, the GMT offset, a globe image, and a section map. Features a world time calculator and a freeware utility to synchronize your PC with an atomic clock.
World Time Zone - A world map with inserted clocks for every time zone in the world.
World Time Zone Map - Black and white map, using the standard time zone names (A - Z). Available in 3 different file types.
Z-Time - Article on the time at 0 degrees longitude. Covers the timezone origin, GMT, UTC, GCT, ZULU and JIG.
Abbey Clock Clinic - Mark Headrick's Horology Page - Traditional horology website with information and mantainance tips. Technical descriptions and troubleshooting of escapements. Grandfather clocks, wall clocks, and watches.
Allan Variance -- Overview by David W. Allan - Core algorithm of international time scale has multiple metrology applications, from atomic clock frequency characterization to definition of the meter. Equation, explanation and publications.
Antique Horology - The Horological Foundation's directory of web sites for watches, clocks, instruments and barometers.
Clocks and Time - Horological index for organizations, clock and watch museums, related software, mailing lists and links. Maintained by Gordon T. Uber.
Cumbria Clock Company - Company specialized in all aspects of work connected with church clocks, public clocks, and tower clocks which includes the full historical restoration of antique clock movements.
David Knight - Watchmaker from UK - Articles and pictures of the first two watches made by David Knight. Rich artistic pictures.
Daylight Saving Time - History of daylight saving time and how we use it to save energy.
Hampton Court Clock - The story of the famous Astronomical clock at Hampton Court Palace. By the author of the original official guide books with the extra omitted information.
The History of Clocks and Watches - Learn about the history of clocks and watches, and discover the evolution of timekeeping devices from the first primitive sundials to the ultramodern atomic clocks. Includes a timeline.
Horology.com - Horology is the science of time, timekeeping and timekeepers. Organized collection of links to horological websites globally.
24 hour analog clocks - The 24 hour analog clock and watch site. History, software, and the places to find clocks with 24 h dials.
How Stuff Works: Time - Complete five-part explanation of time and how it is measured, including information about clocks, time zones, calendars, BC and AD.
How The Days of the Week Got Their Names - A short history of the week and each day of the week.
Jens Olsen's Astronomical Clock - Description of the restoration of Jens Olsen's Astronomical Clock, a masterpiece in Copenhagen City Hall that consists of 15.448 individual parts.
Layman's Guide to the Gent's Electric Turret Clock - A Layman's Guide to the working and restoration of a Gent's Pulsynetic Waiting Train Electric Pendulum Turret Clock.
Leap Year Calculation for Year 2000 - A response to a VMS problem report giving a detailed explanation of why 2000 is a leap year.
Louis Essen - Autobiography of the physicist who built the world's first operational atomic clock.
Mark Frank's Home Page - Website showing the restoration of a french flat bed tower clock in great detail, step by step, as well as other information and links of tower clock sites.
On Time - The Smithsonian Institute's exhibition on the changing ways we have measured, used, and thought about time over the past three hundred years.
"Orologio" at the St. Mark's Square Tower, Venice - Antica Orologeria Zamberlan - Website of Antica Orologeria Zamberlan, Italy. Extensive technical and historical explanation of the restoration and controversy of the "Orologio" Tower at St. Mark's Square, Venice.
Pocket Horology - National chapter of the NAWCC dedicated to collaborative research on the history and horology of pocket watches.
Pulsynetic Electric Clocks - Description, pictures and diagrams of many of the horological products made before 1945 By Gent's of Leicester GB, including a rare Observatory controlled transmitter.
R.A. Braithwaite - Educational site Elliott clocks, how they are built and how to look after them.
UNITAS Reference Site - UNITAS wristwatch and pocketwatch movements from 1898 to the present.
International Standard Date and Time Notation - by Markus Kuhn - An introduction to ISO 8601, the YYYY-MM-DD date and the 24-hour time notation, with notes on week numbers and on implementation.
The Best Of Dates, The Worst Of Dates - Just because Y2K is over, doesn't mean programmers are done creating date bugs - covers many date and time issues, especially ISO 8601 - by Gilbert Healton.
Calculating the ISO week number - by Jan Stout. - WeekNumber Calculation Explanation.
Changing Your Operating System's Default Date Format - Changing your operating system's default date format to use four-digit years - University of California at Berkeley.
The Code Project: C# Programming - Free source code and tutorial for a Gregorian Date To ISO Date Converter for Windows.
Date and Time Notation - Macintosh Procedure for ISO 8601 Format - Setting up your Mac to use the Year-Month-Day date format. Instructions are for MAC OS 7, but are easily adapted for later versions.
Date and Time Notation - Windows Procedure for ISO 8601 Format - Setting up your PC to use the Year-Month-Day date format. Instructions are for Windows 95, but are easily adapted for later versions.
Date and Time on the Internet - A proposal to use the ISO date format for Internet applications - by Chris Newman.
Date and Time on the Internet - Timestamps - Document: draft-ietf-impp-datetime-05 - An updated proposal to use a limited subset of ISO-compliant date formats for date stamps on the Internet - by Chris Newman.
Date and Time on the Internet: Timestamps - RFC 3339 defines a date and time format for use in Internet protocols that is a profile of the ISO 8601 standard for representation of dates and times using the Gregorian calendar - by Graham Klyne and Chris Newman [FTP].
Date and Time: Week Numbers - Windows date and time locale tables sorted both by country order and by definition order - by Peter J Haas in Germany.
Dated Material - Is the Y2K Problem Really Over? - Discussion about the use and misuse of various date formats - Intelligent Enterprise Magazine - Celko.
Delphi 32 - Components: Date & Time: Clocks - ISO Week Number (Program Code) - Here's some code that generates the weeknumber for a given date in accordance with ISO standard 8601:1988 (European Standard EN 28601).
Discussion About the ISO 8601 Standard - About 200 people worldwide, who already use and promote the ISO 8601 Year-Month-Day date format have formed this discussion group. Go here for help and advice, or for general discussion. Message archive can be browsed. If you wish to join in, there are options to participate via the Web-based front-end, or subscribe via email.
Implementation of the ISO 8601 Standard - A list of countries around the world that have adopted the ISO 8601 standard, also lists equivalent national standards numbers where applicable.
Info on ISO 8601, the date and time representation standard - A short description of and motivation for ISO 8601, the date and time representation standard, with links to more detailed resources - by Jukka Korpela in Finland.
International Date Format Campaign - Describes and lists many reasons why the ISO 8601 standard should be more widely adopted in Computing, on the Internet, and in everyday life - by Steve Adams in England.
ISO 8601 - A short introduction to the ISO 8601 format.
ISO 8601 - The Right Solution - The wonderful thing about the computer industry, it is said, "If you like standards, there are a lot to choose from". Provides useful information and background about date format issues.
ISO 8601 compliant website button - A button to place on an iso-8601 compliant website.
ISO 8601 Date and Time - Converting and Implementing - How to implement the use of the Year-Month-Day Date format in various computer systems - includes some programming examples and the 'Date Format Poll' - by Nikolai Sandved in Norway.
ISO 8601 Date/Time Representations - A simple introduction to ISO 8601 date and time formats - University of Wellington in New Zealand.
ISO 8601: the Right Format for Dates - A short description, and guide to usage, of the ISO 8601 format, with some links to further resources.
The ISO Date Format - Discussion of formats for expressing dates, with particular reference to the ISO 8601 date format - by Peter Meyer.
ISO note on the standard - Brief description of the standard from the publishers themselves.
ISO Week Algorithm - An algorithm for converting Gregorian Calendar Dates to the ISO 8601 Week Date format (Y2K Compliant).
The ISO Week Date Calendar - A calendar of weeks based on the ISO 8601 week notation - convert any date into week number and day number.
Issues about Date and Time - by Clive D.W. Feather.
Mac OS X 10.0: How to Set Date and Time to ISO 8601:1988 Standard - Apple support document.
The Many Dates and Times of Perl - A tour of the many date and time handling modules on the CPAN - by Dave Rolsky.
The Mathematics of the ISO 8601 Calendar - A comprehensive document covering how week numbers are calculated using the ISO 8601 calendar system. Includes links to many further resources.
New Date - A private site about the advantages of using ISO 8601-style dates.
Problem F - Standard Dates (50 Points) - A problem set for computer studies students involving programming using the ISO 8601 date format.
Project 2038 FAQ - Description of computer problems with date/time calculations coming in year 2038.
Schema Time Changes (Draft) - Useful information about date and time - by M. Davis.
Standards for Representing Dates - Useful overview and discussion on adopting ISO standards and four-digit year formats as part of Y2K readiness and future-proofing of software - University of California at Berkeley.
Standards to be obeyed by the masses: Representing temporal and monetary data on the web - [Text/PDF: 50KB] - A well researched paper into the usage of various Date and Time, and Monetary, formats on the Internet which recommends the widespread adoption of ISO 3166, ISO 4217, and ISO 8601 - by Gerhard Knolmayer.
UN/ECE Trade Facilitation Recommendation 07 - The United Nations Economic Commission for Europe - Working Party on Facilitation of International Trade Procedures - Recommendation 07 - Numerical Representation of Dates, Time and Periods of Time.
Use International Date Format - How and why to use international date format in your document - from the W3C QA section.
Use ISO 8601 and Drop mm/dd/yy and am/pm - Justin JIH, a Taiwanese American, sets out the reasons why adopting the YYYY-MM-DD date format is preferred. Includes useful links to further resources.
Using ISO 8601 Dates - ISO 8601 Dates: What they are and why they're good - University of Illinois at Chicago in the USA.
W3C Date and Time Formats - Defines a profile of ISO 8601 referenced by the W3C HTML recommendation.
W3C I18N Q&A: Date formats - Discussion of date formats for internationalisation.
Week Numbers In Excel - How to calculate absolute week numbers, Excel week numbers and ISO week numbers (with Formula and VBA). Links to other ISO 8601 related materials.
54 Weeks in 2000 : Another Y2K Problem! - A short discussion about week numbering, showing how the ISO 8601 standard had fixed a Y2K problem, long before it was noticed in other non-ISO week-numbering schemes.
Year 2000 Readiness - Research Resources - International Date Standard - K-State Year 2000 Research Resources - Indepth: International date notation standards.
The Y2K Problem, UIC, and You - Describes Year 2000 fixes for computer systems, mainly based on using the ISO 8601 standard for dates.