the.com/caching
betting that the recent past predicts the near future, so you don't do the work twice.
means storing a copy of data somewhere faster to fetch than its original source, so repeat requests skip the slow part.
from from french cacher, to hide — 19th-century explorers cached supplies in secret spots to retrieve later; computing borrowed the word in the 1960s for hidden fast memory between cpu and main storage.
invalidation problemthere are only two hard problems: naming and cache invalidation.
cpu cachesl1 cache is roughly 100x faster than ram.
browser cachereloads your face-melting gif without re-downloading it.
stale data riskthe fastest wrong answer is still wrong.