The set of 128 special characters that includes accents, graphics and symbols. Each font has a different set of extended characters. To see the range and to use a particular character in the set, start the Character Map utility that's provided with Windows. For the technically minded, the normal range of characters such as A to Z, numbers and punctuation each have a code assigned called an ASCII number. For example, the letter a has an ASCII code of 97 in any font. The ASCII codes are only defined for the code numbers between 0 and 127. The characters represented by the ASCII codes between 128 and 255 are the special characters.
If you want to enter any character into a document, in Word Pad say, you can directly type in its ASCII code number rather than using the Character Map utility. For example, if you are writing a letter in French, you would need the é character. This has an ASCII code of 130. To enter this, hold down the Alt key and enter 130 on the numeric keypad, release the Alt key and the character will appear.