A cache (pronounced CASH) is a place to store something temporarily. The files you automatically request by looking at a Web page are stored on your hard disk in a cache subdirectory under the directory for your browser (for example, Internet Explorer). When you return to a page you've recently looked at, the browser can get it from the cache rather than the original server, saving you time and the network the burden of some additional traffic. You can usually vary the size of your cache, depending on your particular browser.
Computers include caches at several levels of operation, including cache memory and a disk cache. Caching can also be implemented for Internet content by distributing it to multiple servers that are periodically refreshed. (The use of the term in this context is closely related to the general concept of a distributed information base.)
Altogether, we are aware of these types of caches:
- International, national, regional, organizational and other "macro" caches to which highly popular information can be distributed and periodically updated and from which most users would obtain information.
- Local server caches (for example, corporate LAN servers or access provider servers that cache frequently accessed files). This is similar to the previous idea, except that the decision of what data to cache may be entirely local.
- Your Web browser's cache, which contains the most recent Web files that you have downloaded and which is phyically located on your hard disk (and possibly some of the following caches at any moment in time)
- A disk cache (either a reserved area of RAM or a special hard disk cache) where a copy of the most recently accessed data and adjacent (most likely to be accessed) data is stored for fast access.
- RAM itself, which can be viewed as a cache for data that is initially loaded in from the hard disk (or other I/O storage systems).
- L2 cache memory, which is on a separate chip from the microprocessor but faster to access than regular RAM.
- L1 cache memory on the same chip as the microprocessor.
Also see: buffer, which, like a cache, is a temporary place for data, but with the primary purpose of coordinating communication between programs or hardware rather than improving process speed.