Prototype-based programming

Prototype-based programming is a style of object-oriented programming in which behaviour reuse (known as inheritance) is performed via a process of reusing existing objects via delegation that serve as prototypes. This model can also be known as prototypal, prototype-oriented, classless, or instance-based programming. Delegation is the language feature that supports prototype-based programming.

Lets use the idea of "fruit" as one example. A "fruit" object would represent the properties and functionality of fruit in general. A "banana" object would be cloned from the "fruit" object, and would also be extended to include general properties specific to bananas. Each individual "banana" object would be cloned from the generic "banana" object.

The first prototype-oriented programming language was Self, developed by David Ungar and Randall Smith in the mid-1980s to research topics in object-oriented language design. Since the late 1990s, the classless paradigm has grown increasingly popular. Some current prototype-oriented languages are JavaScript (and other ECMAScript implementations, JScript and Flash's ActionScript 1.0), Lua, Cecil, NewtonScript, Io, Ioke, MOO, REBOL, Lisaac and AHk.

...
Wikipedia