Luau is a scripting language derived from Lua. It was created for Roblox, an online game platform and game creation system. Luau is backwards compatible with Lua 5.1, meaning Lua 5.1 can be executed within the Luau environment. Luau is used by Roblox game developers to write game code and by Roblox engineers to write large parts of the user-facing application code and also portions of the Roblox Studio editor as plugins.
Luau is open-source and information on it’s source code and associated tools can be found within the Luau Repository.
Luau vs. Lua
The difference between Luau and Lua comes down to performance. Luau has a number of performance optimizations including a fast bytecode interpreter, making it faster and more efficient than Lua. Luau also doesn’t have just-in-time (JIT) compilation since it’s main focus is on stable high performance code and JIT compilation is not available on many platforms Luau runs on. This is different from Lua which has a focus on JIT and has a tracing just-in-time compiler called LuaJIT.