Byzantine fault tolerance has been intensively studied over the past decade as a way to enhance the intrusion resilience of computer systems. However, state-machine-based Byzantine fault tolerance algorithms require deterministic application processing and sequential execution of totally ordered requests. One way of increasing the practicality of Byzantine fault tolerance is to exploit the application semantics, which we refer to as application-aware Byzantine fault tolerance. Application-aware Byzantine fault tolerance makes it possible to facilitate concurrent processing of requests, to minimize the use of Byzantine agreement, and to identify and control replica nondeterminism. In this paper, we provide an overview of recent works on application-aware Byzantine fault tolerance techniques. We elaborate the need for exploiting application semantics for Byzantine fault tolerance and the benefits of doing so, provide a classification of various approaches to application-aware Byzantine fault tolerance, and outline the mechanisms used in achieving application-aware Byzantine fault tolerance according to our classification.