Define the term "cache" in relation to computer architecture.

Cache refers to a specific type of high-speed memory located close to the CPU (Central Processing Unit) that is designed to store frequently accessed data and instructions. Its primary purpose is to speed up data retrieval processes, as accessing data from cache memory is much faster than accessing it from the main RAM or other storage devices. By holding onto the most frequently used data and instructions, cache helps to reduce latency and improve the overall performance of the system.

Effective cache memory helps ensure that the CPU spends less time waiting for data to be loaded from slower memory or storage devices. Generally, there are multiple levels of cache (such as Level 1, Level 2, and Level 3), with Level 1 being the smallest and fastest, residing directly on the CPU chip.

In contrast, other options imply incorrect functions or characteristics of cache. An external hard drive is primarily used for storage, not as high-speed memory. Main storage refers to RAM, which is slower compared to cache memory. Finally, cache is not intended for backup; its primary function is to serve active data for quick access, not to store data long-term.