A "cache hit" occurs when a requested piece of data is found in a cache, which is a smaller, faster storage area that temporarily holds frequently accessed information. This allows systems, such as computers or web servers, to retrieve data quickly without needing to access slower storage options, like hard drives or databases. When a cache hit happens, it improves performance and reduces latency, making applications run more efficiently. For example, when a user visits a website, the browser may store images and scripts in its cache. If the user revisits the site, the browser can load these elements from the cache, resulting in a faster experience.