Smalltalk is a very influential programming language that helped shape the model–view–controller (MVC) pattern for user interface design and fostered a new era in GUIs. However, even for all its pivotal relevance, Smalltalk has been gradually abandoned by most developers and it’s only used by a small community that swears by it. A significant reason why Smalltalk is used today is because of the release of development frameworks for it, especially Seaside, a framework that makes it easy for you to create web apps. 

Smalltalk is an object-oriented, dynamically typed reflective programming language. Smalltalk was created as the language underpinning the "new world" of computing exemplified by "human–computer symbiosis".