Smalltalk
The original object-oriented language — everything is an object, and computation happens through message passing.
dynamic
interpreted
since 1972
oopconcurrent
Smalltalk pioneered the concepts of objects, message passing, garbage collection, and the live IDE environment where you modify running code. Every modern OOP language owes conceptual debt to Smalltalk. Pharo and Squeak keep the tradition alive, and Smalltalk remains widely used in finance and insurance at companies like JP Morgan.