What does "World Position Offset" and "Refraction" mean on Landscape Layer node?

I can’t find anything in the docs about this and I’ve never heard those terms before in regards to a material. Any help or understanding is appreciated!

WorldPosition Offset allows you to manipulate the vertices on a mesh to create movement and other effects, for example it can be used with a sine wave to create an ocean wave simulation (similar to the project in my signature, I use displacement instead but either way would work). Here is some info on that:

Refraction is used in materials such as glass, water, ice etc to allow light to refract on the surface, here is some info on it:

Thanks so much! I’ve read through the docs ten times and I always miss things still.