When writing the date, some prefer to put the month first, still others the day. Some people write the date out in full, others use abbreviations or just numbers. Should dashes or forward slashes be used? How are the months (especially the shorter ones, like March) supposed to be abbreviated?
The United States has a rather unique way of writing the date that is imitated in very few other countries (although Canada and Belize do also use the form). In America, the date is formally written in month/day/year form. Thus, “January 1, 2011” is widely considered to be correct. In formal usage, it is not appropriate to omit the year, or to use a purely numerical form of the date. For example, if you were to write a formal letter for business, you would write out the entire date, including the name of the month (January 1, 2011). Writing it out in full allows for the notation to be understood even by people for whom the month/day/year form is relatively uncommon.
Europeans write the date in a different way. Americans referring to the “Fourth of July” are emulating the British when they use this form. In most of Europe, the date is written out in day/month/year format, also known as “little endian form.” Thus, July 4, 2011 would actually be known as 4/7/11 in short numerical notation. Formally speaking, the date is written similarly to the way it would be written formally in America. For example, July 4, 2011 would simply have the month and day switched around, for 4 July 2011. Notice that in this formal version of the date, there is no comma. The comma separating the date from the year is an Americanism that the Europeans do not follow.
There are other forms of writing the date that are considered perfectly acceptable around the world. The most common of these is known as “big endian” form, which seeks to avoid confusion by placing the year first. Hungary, Sweden, and many of the Asian countries use big endian form when writing the date. January 1, 2011 would be written in this form as 2011 January 1. Again, notice that there is no comma. When writing the day of the week, the American and common European ways of formally writing the date would put the weekday first: “Saturday, January 1, 2011.” However, using the big endian form, the day of the week actually follows the rest of the date. Thus, on a formal piece of writing, you would have 2011 January 1, Saturday.
When writing the date formally, consider your audience. In informal writing, a variety of different forms may be used. When writing the formal date, however, abbreviations are never to be used, so as to avoid confusion. Consider the person to whom you are writing, and use the form with which they are likely the most familiar. Also remember that the American form is widely considered “acceptable” in other countries, although it is rather rare. No one will become confused if you use a different form than what they’re used to—but what they’re “used to” should be your primary objective. Formal writing seeks to be as cordial as possible.