Lua is a very powerful, yet simple interpreter language, which can be easily incorporated into a host program. Lua allows powerful scripts to be written that enhance the host program. These scripts are written, outside of the host program. This means that some of the program code is accessible to the user. Program changes or extensions can be easily incorporated into the system, without having to rebuild the host program. The programming concepts of Lua, allows for very complex programs to be written and run immediately.
For more details, please, see inbuilt help pages