"OOP" is a comon abbreviation for "Object Oriented Programming". The idea derives from Modula and Smalltalk, and was since copied to some extent in most programming languages: C++, Java, Delphi, Visual Prolog and Eiffel all have their own implementation of some sort of "Object Oriented Programming".
From the point of view of Smalltalk and
Squeak OOP that is not Smalltalkish is - at least -
a somewhat emasculated OOP. The Smalltalk and Squeak point of view is often
rendered by the slogan "Everything is an object" - meaning that in
Smalltalk and Squeak whatever can be programmed at all in these languages
must be programmed as some Object, and indeed
any object that is run in the environment inherits
from Object.
Another very important difference between Smalltalkish languages and other
languages is that the objects in Smalltalk can be reprogrammed in the very
environment in which they work.
Glossary -
O