AsciiArt
Basically, AsciiArt consists of pictures which are created without using graphic elements. They are "non-graphical graphics". Its palette is limited to the symbols and characters that is available to you on your (QWERTYAZERTY/etc..)-keyboard.
The simplest forms of AsciiArt are the Smiley and its kin, little two or three character combinations for expressing emotion in text. :)