"The quick brown fox jumps over the lazy dog" is a sentence that uses every letter in the Latin alphabet
at least once. As such, it is frequently used for typography
tests and, by the nature of its including every letter in the alphabet, is called a pangram
("all letters"). It is believed to be the most popular pangram in use for several reasons, among them the fact that it is short and easy to remember and the fact that it has been in use for so long.
The phrase first came into being when Western Union needed something short and concise that would effectively test all the characters on its communications equipment. It has been suggested on several message boards and forums that the original test phrase was "The quick brown fox jumped over a lazy dog's back 1234567890 times," so that the numbers could also be tested.
While "the quick brown fox jumps over the lazy dog" is probably the most oft-used English pangram today, other languages have their own share of these phrases. The lazy dog pangram is used in Microsoft Windows font files in order to depict what every letter looks like in that particular font. Similarly, several font download websites use the phrase as a default for the same reasons. Some, such as daFont, allow the user to enter their own text to replace the pangram -- that way, they don't need to download the font in order to see how a different phrase appears.
Using a Windows installation in another language? Microsoft uses a number of pangrams in other languages as well. Wikipedia also has a comprehensive list of multilingual pangrams. Those in languages that use different alphabets are perhaps the most interesting, as certain alphabets (such as the Cyrillic alphabet) evolved over time to include new letters. The pangrams originated during the days of telegraph usage, often before new letters were used.
If I'm not mistaken, Apple products use a similar format when displaying fonts, but with a different pangram. If anyone could elaborate on this, I'd appreciate it.
The phrase also took on new life as part of Threadless's "Joy of Text" competition. An Australian artist named Pascal Hoayek placed third with his depiction of a quick brown fox jumping over a lazy dog on a yellow background -- the animals were formed by the letters that spelled out the phrase. This has remained one of Threadless's best-selling designs to date; it is currently sold out and a number of the site's users are clamouring for a reprint. Hoayek called his design "=rand( )," a reference to the Microsoft Word "hack" that jaybonci alluded to above -- typing "=rand()" into Word and hitting enter produces the phrase automatically.
An OnTrack forum with a particularly long URL