Smalltalk is an object-oriented programming language and development environment. Applications are composed of different kinds of objects which communicate to one another by sending messages. The response to the message is determined by methods.

A message is called unary when it takes no arguments, binary when it takes a single argument and keyword when one or more arguments as indicated by semicolons (:).

The VA Smalltalk development environment supports four types of software components:

Classes are placed in a superclass-subclass hierarchy. In this way, a class API can be maintained and refined, promoting object reuse. Classes higher in the hierarchy are more general purpose (e.g. Object) and classes lower in the hierarchy are more specific (e.g. Integer is more specific than Number.)