From LoTROInterface Wiki
Lord of the Rings Online provides us with the option to modify the default user interface and now create lua scripts. LoTROInterface is dedicated to providing not only a large collection of plugins & interfaces created by many talented authors, but also help you learn to add on or create your own as well.
Writing LoTRO Lua Plugins for Noobs contains an excellent series of posts by Garan and other authors in the Lotro plugin community.
Main article LotRO_API_Reference
LotRO's Lua API consists of four packages, containing various classes, that add onto a basic implementation of Lua (5.1). The implementation of Lua consists of only the math and string libraries, almost entirely for security reasons (i.e. preventing access to a user's computer, running external libraries, etc.). Each of the API's packages has their own specific role, covering everything from managing the plugin itself, to delivering gameplay data and events.
Lotro Mod Manager
The Lotro Mod Manager is an external manager that helps to maintain order amongst plugins. The plugins need to be in the LotroMod format in order to work smoothly and seamlessly.