Memory
The fast, temporary space where a system keeps the information it is actively using.
Glossary
Cache
A small, fast store of recently used information kept close at hand.
In one line
A small, fast store of recently used information kept close at hand.
Also calledfast store
A cache keeps copies of things likely to be needed again soon, so they can be fetched quickly rather than retrieved the slow way each time. It trades a little space for a lot of speed, betting that what was useful once will be useful again.
Many drivers cache results of their work, recognising that the same request often arrives more than once and need not be computed from scratch every time. When the same answer is asked for again, it can be handed over instantly from the nearby copy.
A cache is small on purpose, so it cannot hold everything. This means deciding what to keep and what to let go. When it fills, something must be discarded to make room, and choosing wisely is what makes a cache genuinely helpful rather than merely full.
The risk of a cache is staleness. If the original information changes, the stored copy can fall out of date, so a careful system knows when to trust the cache and when to refresh it. Managing that freshness is the quiet discipline behind every fast, reliable cache.
In practice
In practice, a cache is like keeping the few ingredients you use most on the counter rather than in the back of the pantry. You reach them in a second instead of fetching them each time. A computer keeps its frequently needed data close at hand for exactly the same reason.
