L3 caches, or Level 3 caches, are a type of memory storage used in computer processors to improve performance. They act as a buffer between the CPU and the main memory, storing frequently accessed data and instructions. This helps reduce the time it takes for the CPU to retrieve information, leading to faster processing speeds. Typically larger than L1 and L2 caches, L3 caches are shared among multiple cores in a multi-core processor. This shared design allows for efficient data access across different cores, enhancing overall system performance. L3 caches play a crucial role in modern computing, especially in applications requiring high-speed data processing.