Ruby (programming language)
Ruby has been described as a multi-paradigm programming language: it allows procedural programming (defining functions/variables outside classes makes them part of the root, 'self' Object), with object orientation (everything is an object) or functional programming (it has anonymous functions, closures, and continuations; statements all have values, and functions return the last evaluation). It has support for introspection, reflection and metaprogramming, as well as support for interpreter-based threads. Ruby features dynamic typing, and supports parametric polymorphism.
Object (computer science)
Rather than structure programs as code and data, an object-oriented system integrates the two using the concept of an "object". An object has state (data) and behavior (code). Objects can correspond to things found in the real world. So for example, a graphics program will have objects such as "circle", "square", "menu". An online shopping system will have objects such as "shopping cart, customer, product". The shopping system will support behaviors such as "place order", "make payment", and "offer discount". The objects are designed as class hierarchies. So for example with the shopping system there might be high level classes such as "electronics product", "kitchen product", and "book". There may be further refinements for example under "electronic products": "CD Player, DVD player", etc. These classes and subclasses correspond to sets and subsets in mathematical logic.