The concept of making an electronic circuit unaffected by, or undergo graceful degradation in the face of, errors. Fault tolerance can be seen as a supplement to fault avoidance, the art of preventing faults to occur in the first place.

Conventional methods of fault tolerance often use redundancy, in other words extra, "reserve" hardware so faulty circuits can be shut off. In the later years, the possibility of using evolutionary hardware for fault tolerance is being investigated.