What is the difference between Caching and Memoization?
CachingTerminologyMemoizationCaching Problem Overview
I would like to know what the actual difference between caching and memoization is.
As I see it, both involve avoiding repeated function calls to get data by storing it.
What's the core difference between the two?
Caching Solutions
Solution 1 - Caching
Memoization is a specific form of caching that involves caching the return value of a function based on its parameters.
Caching is a more general term; for example, HTTP caching is caching but not memoization.
Wikipedia says:
> Although related to caching, memoization refers to a specific case of this optimization, distinguishing it from forms of caching such as buffering or page replacement.
Solution 2 - Caching
As I have seen them used, "memoization" is "caching the result of a deterministic function" that can be reproduced at any time given the same function and inputs.
"Caching" includes basically any output-buffering strategy, whether or not the source value is reproducible at a given time. In fact, caching is also used to refer to input buffering strategies, such as the write-cache on a disk or memory. So it is a much more general term.
Solution 3 - Caching
I think term caching is usually used when you store results of IO operations, or basically any data that is coming to you from the outside (files, network, db queries). Term memoization usually applies to storing results of your own computations, for example in the context of dynamic programming.
Solution 4 - Caching
Memoization is a special form of caching the result of a deterministic function. This means that caching the result outside the function is not memoization because the function would have to mutate the cache when computing a new result (not already in the cache) so it would not be a (pure) function anymore. Memoization generally implies passing the cache as an additional argument (in an helper function). Memoization will optimize functions that need to compute values several times for a single access. Caching will optimize functions that are called several times with the same parameters. In other words, Memoization will optimize the first access whether caching will only optimize recurrent accesses.
Solution 5 - Caching
I would like to add to the other great answers that memoization is also known as tabling. I think it is also important to know that term for those who learn what memoization and caching are.