From http://www.w3schools.com (Copyright Refsnes Data)

Web Quality - Internationalization

The Internet is International

With the Internet follows an absolute requirement to interchange data in a multiplicity of languages, which in turn utilize a bewildering number of characters.

H. Alvestrand, The Internet Engineering Task Force (IETF), January 1998.

International Character Sets

All W3C standards (since 1996), including HTML, XHTML, and XML defines an internal character set called Unicode (ISO 10646).

All modern web browsers are using this (Unicode) character internally. Most documents transmitted over the Internet do not use the Unicode character set.

Because of this, Internet clients (browsers) and Internet servers must have a way to agree about the character set used in the communication between them.

Labeling each document with the character set in use, is very important to the quality of your web site.

For your HTML and XHTML pages always use the following meta element inside the <head> element:

<meta http-equiv="Content-Type" content="text/html;charset=X" />

Replace X with the character set you use, like ISO-8859-1, UTF-8, or UTF-16.

International Dates

Don't use dates like "04-03-02".

The date above could mean the second day of March in 2004. It could also mean the fourth day of March in 2002. Or even the third day of April in 2002.

The international standard organization (ISO) has defined an international standard format for dates as "yyyy-mm-dd", where yyyy is the year, mm is the month and dd is the day.

When you use this ISO format, you can expect most visitors to understand your dates.