Ans. Cache coherence refers to the consistency of shared data in a multi-core processor system. In such systems, each core has its own cache, and when multiple cores access the same memory location simultaneously, there is a possibility of data inconsistency. Cache coherence protocols are used to ensure that all cores observe a consistent view of shared data. These protocols manage the invalidation and updating of cache lines to maintain data coherence and prevent data corruption or incorrect results due to concurrent access.