Selective coordination of circuit breakers is important because it ensures that a fault or overload in one part of an electrical system will not cause a power outage in the entire system. It involves carefully coordinating the trip settings of the circuit breakers so that only the circuit breaker closest to the fault will trip, isolating the problem and minimizing the number of circuits affected. This improves the overall reliability and safety of the electrical system by preventing widespread power outages, reducing the risk of fire, and protecting sensitive equipment.