Source : Free On-Line Dictionary of Computing

Smalltalk
     
         The pioneering {object-oriented programming} system
        developed in 1972 by the Software Concepts Group, led by {Alan
        Kay}, at {Xerox PARC} between 1971 and 1983.  It includes a
        language, a programming environment, and an extensive object
        library.
     
        Smalltalk took the concepts of {class} and {message} from
        {Simula-67} and made them all-pervasive.  Innovations included
        the {bitmap display}, windowing system, and use of a {mouse}.
     
        The {syntax} is very simple.  The fundamental construction is
        to send a message to an {object}:
     
        	object message
     
        or with extra parameters
     
        	object message: param1 secondArg: param2 .. nthArg: paramN
     
        where "secondArg:" etc. are considered to be part of the
        message name.
     
        Five pseudo-variables are defined: "self", "super", "nil",
        "true", "false".  "self" is the receiver of the current
        message.  "super" is used to delegate processing of a message
        to the {superclass} of the receiver.  "nil" is a reference to
        "nothing" (an instance of UndefinedObject).  All variables
        initially contain a reference to nil.  "true" and "false" are
        {Booleans}.
     
        In Smalltalk, any message can be sent to any object.  The
        recipient object itself decides (based on the message name,
        also called the "message selector") how to respond to the
        message.  Because of that, the {multiple inheritance} system
        included in the early versions of Smalltalk-80 appeared to be
        unused in practice.  All modern implementations have single
        inheritance, so each class can have at most one superclass.
     
        Early implementations were {interpreted} but all modern ones
        use {dynamic translation} (JIT).
     
        Early versions were Smalltalk-72, Smalltalk-74, Smalltalk-76
        (inheritance taken from Simula, and concurrency), and
        Smalltalk-78, {Smalltalk-80}.  Other versions include {Little
        Smalltalk}, {Smalltalk/V}, {Kamin's interpreters}.  Current
        versions are {VisualWorks}, {Squeak}, {VisualAge}, {Dolphin
        Smalltalk}, {Object Studio}, {GNU Smalltalk}.
     
        See also: {International Smalltalk Association}.
     
        {UIUC Smalltalk archive (http://st-www.cs.uiuc.edu/)}.
        {FAQ (http://XCF.Berkeley.EDU/pub/misc/smalltalk/FAQ/)}.
     
        {Usenet} newsgroup: {news:comp.lang.smalltalk}.
     
        ["The Smalltalk-76 Programming System Design and
        Implementation", D.H. Ingalls, 5th POPL, ACM 1978, pp. 9-16].
     
        (2001-09-11)