ASCII The American Standard Code for Information Interchange (ASCII) is a code for exchanging text among computers and programs. The standard ASCII character set corresponds to standard keyboard characters. You can use the extended ASCII character set to insert special characters in documents. To insert a special character, turn on NumLock, then hold down Alt and type the numeric code for that character, using the numbers on the numeric keypad. An ASCII file is a text-only file; it has no formatting.