There&#x27;s more details in the presenter notes:<p>&gt;I won’t get into much detail about threading, but imagine how the OpenGL skynet-state-machine interacts with multiple threads. GLium ensures only a thread-specific OpenGL context is used on any particular thread.<p>&gt;By making everything neither Send nor Sync, it prevents you from using resources created by one thread in another, enforcing OpenGL semantics at compile-time.<p>Basically any type without Send+Sync traits will not work with existing threading APIs(since they require combinations of Send+Sync based on threading semantics) forcing API calls to be done on the right thread.