A CPU cache is a small, high-speed storage area located inside or near the central processing unit (CPU) of a computer. It temporarily holds frequently accessed data and instructions, allowing the CPU to retrieve them quickly without needing to access the slower main memory (RAM). This speeds up processing and improves overall system performance. There are typically multiple levels of caches, labeled as L1, L2, and sometimes L3. The L1 cache is the smallest and fastest, while the L2 and L3 caches are larger but slightly slower. Together, these caches help reduce latency and enhance the efficiency of data processing in computers.