Cache memory is a fast and temporary memory that stores frequently used data or instructions for quick access by the processor. It is located between the processor and the main memory in a hierarchy of memory systems. The purpose of cache memory is to reduce the time required to access data from the main memory, which is slower and larger than cache memory.

Cache memory stores a copy of the most frequently used data from main memory in a small and fast memory cache. When the processor needs to access data or instructions, it checks if it is already in the cache memory. If it is, the processor can access it quickly without retrieving it from the main memory. This process is known as a cache hit. If the data is not in the cache memory, the processor must retrieve it from the main memory, which takes more time. This process is known as a cache miss.

Cache memory is typically organized in a set-associative or fully associative manner. Data is divided into sets in set-associative cache memory, each with multiple cache lines. Any data can be stored in any cache line in fully associative cache memory. The size of cache memory is typically smaller than the main memory, which makes it expensive to implement but highly effective at improving computer performance.

In summary, cache memory is a type of high-speed memory that stores frequently accessed data and instructions and is used to improve computer performance by reducing the time required to access data from main memory.