Smalltalk was one of many object-oriented programming languages based on Simula. Smalltalk was also one of the most influential programming languages. Virtually all of the object-oriented languages that came after—Flavors (Flavors (programming language)),Flavors A non-hierarchical approach to object-oriented programming 
CLOS, Objective-C, Java (Java (programming language)), Python (Python (programming language)), Ruby (Ruby (programming language)),About Ruby and many others—were influenced by Smalltalk. Smalltalk was also one of the most popular languages with the Agile Methods, Rapid Prototyping (Rapid application development), and Software Patterns (Software design pattern)Where Did Refactoring Come From? communities. The highly productive environment provided by Smalltalk platforms made them ideal for rapid, iterative development - wikipedia
Smalltalk emerged from a larger program of ARPA (Advanced Research Projects Agency) funded research that in many ways defined the modern world of computing. In addition to Smalltalk working prototypes of things such as hypertext, GUIs, multimedia, the mouse, telepresence, and the Internet were developed by ARPA researchers in the 1960s.DARPA / ARPA Engelbart's Role in Early Computer Networking Alan Kay (one of the inventors of Smalltalk) also described a tablet computer he called the Dynabook which resembles modern tablet computers like the iPad.The Early History of Smalltalk
Smalltalk environments were often the first to develop what are now common object-oriented software design patterns. One of the most popular is the Model–view–controller pattern for User Interface design. The MVC pattern enables developers to have multiple consistent views of the same underlying data. It's ideal for software development environments, where there are various views (e.g., entity-relation, dataflow, object model, etc.) of the same underlying specification. Also, for simulations or games where the underlying model may be viewed from various angles and levels of abstraction.[ A Cookbook for Using the Model-View-Controller User Interface Paradigm in Smalltalk -80]
In addition to the MVC pattern the Smalltalk language and environment were tremendously influential in the history of the Graphical User Interface (GUI) and the What You See Is What You Get (WYSIWYG) user interface, font editors, and desktop metaphors for UI design. The powerful built-in debugging and object inspection tools that came with Smalltalk environments set the standard for all the Integrated Development Environments, starting with Lisp Machine environments, that came after.Our Influence