Prefabs are a Unity concept.

Since not all readers have Unity experience and thus know what prefabs are, it seems better to clarify it here.

getting_started/step_by_step/instancing_continued.rst

@@ -9,7 +9,7 @@ Recap
 Instancing has many handy uses. At a glance, with instancing you have:
 
 -  The ability to subdivide scenes and make them easier to manage.
--  A more flexible alternative to prefabs (and much more powerful given that
+-  A more flexible alternative to prefabs you might know from Unity (and much more powerful given that
    instances can be nested).
 -  A way to organize and embed complex game flows or even UIs (in Godot, UI
    Elements are nodes, too).