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:
          (__)
          (oo)
   /-------\/              O
  / |     ||     /o)\     /H\ 
 *  ||----||     \(o/     / \
    ~~    ~~
       Cow     Yin/Yang?  Person
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".