AllFonts displays the phrase "The quick brown fox jumps over the lazy dog" in
all of ANSI_CHARSET and SYMBOL_CHARSET typefaces that are available on your system.
What use is this? Its an easy way to see what text looks like without having to keep selecting text and changing the typeface.
When you have picture fonts like Wingdings it very difficulty to see what pictures are available in that font, so AllFonts will also display all the characters within a typeface.
If you are interested in what is meant by CHARSET, please see
here.
You can enter any character into an application by holding down the ALT key and enetring the code as three digits from the keypad, if necessary add leading zeroes