Why use tessellation instead of a high resolution terrain

Like the subject…I am wondering why one should use tessellation instead of a dense high resolution terrain or any other object. What is the benefit?
Regards! T

Benefits are quality, speed and flexibility.

For best performance you can tessellate the geometry that’s closest to the camera rather than having a lot of polygons that don’t make much of a difference to how things look.

Like Darth said, tessellation basically has LOD control that is flexible, as well you can turn off tessellation at any time, but you cant do that with a high density mesh.