A Plugin in Loop will be able to modify existing behavior of the language or extend it with new behavior.
Plugins vs Packages
There's a fundamental difference between plugins and packages in Loop. While a Package can be created within the Loop Language and use existing components of the language a Plugin can not. A plugin is written in any language that supports the C API and needs to be compiled to a dynamic library (.dll, or .so) before being used within Loop. We reccomend writing your plugin in Rust.
A Plugin is also more powerful due to this. You can use any Rust functionality and export it to be used within Loop.