A "Cache Hit" occurs when a requested piece of data is found in a cache, which is a temporary storage area that holds frequently accessed information. Caches are used in various computing systems, including web browsers, CPU, and databases, to speed up data retrieval and improve performance. When a cache hit happens, the system can quickly deliver the data without needing to access slower storage options. This process enhances efficiency because accessing data from a cache is much faster than retrieving it from the original source, such as a hard drive or a remote server. A higher cache hit rate indicates better performance, as it means that more requests are being fulfilled directly from the cache, reducing latency and resource usage.