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From Lua's About page:
What is Lua?
Lua is a powerful, fast, lightweight, embeddable scripting language.
Lua combines simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics. Lua is dynamically typed, runs by interpreting bytecode for a register-based virtual machine, and has automatic memory management with incremental garbage collection, making it ideal for configuration, scripting, and rapid prototyping.
Please note that the official name of this programming language is Lua (a Portuguese word for Earth's moon). It is not an acronym -- it is not spelled LUA.