Explain the Producer-Consumer problem and its solution.

Classic synchronization problem: producers add items to bounded buffer, consumers remove them. Challenges: don't add to full buffer, don't remove from empty, ensure mutual exclusion. Solution uses semaphores: mutex (binary, for buffer access), empty (counting, initialized to buffer size), full (counting, initialized to 0). Producer: wait(empty), wait(mutex), add, signal(mutex), signal(full). Consumer: wait(full), wait(mutex), remove, signal(mutex), signal(empty).