Date and time notation around the world varies.

An approach to harmonise the different notations is the ISO 8601

ISO 8601

ISO 8601 Data elements and interchange formats – Information interchange – Representation of dates and times is an international standard covering the exchange of date and time-related data. It was issued by the International Organization for Standardization and was first published in 1988...

. (See also ISO 8601 usage

ISO 8601 usage

On the Internet, the World Wide Web Consortium uses ISO 8601 in defining a profile of the standard that restricts the supported date and time formats to reduce the chance of error and the complexity of software....

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Since the Internet

Internet

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

 is a main enabler of communication between people with different date notation background, and software is used to facilitate the communication, RFC

Request for Comments

In computer network engineering, a Request for Comments is a memorandum published by the Internet Engineering Task Force describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.Through the Internet Society, engineers and...

 standards and W3C tips and discussion paper were published.

• RFC 822 "Standard for the Format of Arpa Internet Text Messages"
  • published 1982-08-13
  • e.g. used for email
  • format: [day ,] 20 Jun 82 14:01:17
• RFC 2445 "Internet Calendaring and Scheduling Core Object Specification"
  • format: 19960401T235959Z
• RFC 3339 "Date and Time on the Internet: Timestamps"
  • published July 2002
  • intended use: new internet protocols
  • format: 1982-06-20
• W3C: "Use international date format (ISO)"