Lua is a programming language originally designed for extending applications,
but also frequently used as a general-purpose, stand-alone language. Lua
combines simple procedural syntax (similar to Pascal) with powerful data
description constructs based on associative arrays and extensible semantics.
Lua is dynamically typed, interpreted from bytecodes, and has automatic memory
management with garbage collection, making it ideal for configuration,
scripting, and rapid prototyping. 

A fundamental concept in the design of Lua is to provide meta-mechanisms for
implementing features, instead of providing a host of features directly in
the language. For example, although Lua is not a pure object-oriented
language, it does provide meta-mechanisms for implementing classes and
inheritance. Lua's meta-mechanisms bring an economy of concepts and keep the
language small, while allowing the semantics to be extended in unconventional
ways. Extensible semantics is a distinguishing feature of Lua. 

Lua is implemented as a small library of C functions, written in ANSI C, and
compiles unmodified in all known platforms. The implementation goals are
simplicity, efficiency, portability, and low embedding cost. 

WWW: http://www.tecgraf.puc-rio.br/lua/