Cache is a hardware or software component that stores data so that future requests for that data can be served faster. It is a temporary storage area that holds frequently accessed data, reducing the time it takes to access and retrieve the data from its original location.
Caching can be implemented at different levels in a computer system, including:
- Web caching – A web cache is a component that stores web pages, images, and other content so that future requests for that content can be served faster. Web caching is often used in web browsers, content delivery networks (CDNs), and proxy servers.
- CPU caching – CPU caching is used to store frequently accessed instructions and data in a faster cache memory, such as the L1, L2, and L3 caches in modern CPUs.
- Disk caching – Disk caching is used to store frequently accessed data on a faster storage medium, such as RAM, to improve disk read and write performance.
- Application caching – Application caching is used to store frequently accessed data, such as database queries or API responses, in memory to reduce the need for repeated requests to the original data source.
Caching can significantly improve the performance of computer systems by reducing the time it takes to access and retrieve data. However, caching also introduces the risk of stale data, where cached data is outdated or invalid. To prevent stale data, caching systems often use techniques such as cache invalidation, expiration times, and conditional requests to ensure that cached data is accurate and up-to-date.