What Is Lua?

Lua is a lightweight, high-level, multi-paradigm scripting language built for embedding inside larger applications written in C, C++, or other host languages. Created in 1993 by Roberto Ierusalimschy, Waldemar Celes, and Luiz Henrique de Figueiredo at PUC-Rio in Brazil, Lua compiles to compact bytecode executed on a register-based virtual machine, uses automatic garbage collection, and centers its data-modeling power on a single flexible structure called the table. Unlike general-purpose languages meant to stand alone, Lua was explicitly designed to be dropped into a host program and extended through a small, well-documented C API.

Lua was designed from the outset around three guiding principles: portability, simplicity, and small size. The reference implementation is written in strict ANSI C with no external dependencies, which lets it compile on virtually any platform with a C compiler, from desktop operating systems to games consoles and microcontrollers. The interpreter and standard libraries together compile to roughly 250 KB, and the language deliberately ships with a minimal core, pushing anything not essential — like object orientation or complex data structures — into patterns built from tables rather than built-in syntax. The name itself means 'moon' in Portuguese, chosen as a successor to an earlier PUC-Rio data-description language called 'Sol' ('sun').

Because it's small, fast, and easy to embed, Lua has become the scripting layer of choice across a wide range of industries. In games, it powers World of Warcraft's addon system, Roblox's entire scripting model, and titles like Angry Birds and the Baldur's Gate series. Outside games, Adobe uses Lua to script plugins for Photoshop Lightroom, the Nginx-based OpenResty platform uses it to handle web requests at scale, Redis exposes Lua for atomic server-side scripting, and the Neovim text editor uses Lua as its primary configuration and plugin language. In each case, Lua isn't the application itself — it's the layer that lets developers or end users customize behavior without recompiling the host.

A handful of traits define Lua as a language. It's dynamically typed, so variables carry no type annotation and can hold any value at runtime. Its only built-in data structure is the table — an associative array that can represent lists, dictionaries, objects, and even modules, since Lua has no separate array, class, or object syntax. Functions are first-class values that can be stored in variables, passed as arguments, and returned from other functions, which enables closures and callback-driven APIs. Lua also natively supports coroutines, giving it lightweight, cooperative multitasking without requiring an operating system thread for every concurrent task.