ASCII art basically consists of pictures pieced together from characters (preferrably from the set defined by ASCII). They can be created with any text editor. Most require a non-proportional font for correct viewing.
The simplest forms of ASCII Art are the smiley and its kin: little two- or three-character combinations for expressing emotion in text. :-) More complex examples used several lines of text to draw large symbols or crude representations or more complex figures. It was popular to put such art in one's signature file to be included in all your e-mail and Usenet postings. Some common examples:
Some types ignore the particular shape of the characters and treat them as more-or-less filled boxes:
_a, _yQa. _qTWW( je`?QX: <d+ -3Wm; _qos_s%mWw, a2?????TWW( sd( -?Qm;. .amm; .xmWmc """""` """""""
ASCII Art is and was used wherever text can be more readily printed or transmitted than graphics. This includes typewriters, teletypes, computer terminals, early computer networking, e-mail and Usenet news messages.
Animated ASCII art is possible by embedding ANSI escape sequences for cursor movement into the "picture".
See ASCII Art FAQ.