In information technology, cache refers to a fast buffer memory that helps to avoid (repeated) accesses to a slow background medium or costly recalculations. Data that has already been loaded or generated once remains in the cache so that it can be retrieved more quickly from it when needed later. Also, data that is likely to be needed soon can be retrieved in advance from the background medium and made available in the cache for the time being.
As a rule, the cache and its substitute function for the addressed background medium remain hidden from the user. The user of the background medium does not need to know the size or function of the cache, because the cache is not directly addressed. The user retrieves data from a background medium, e.g. a hard disk, but instead the cache answers in exactly the same way as the background medium would have answered, i.e. delivered data. Because of the invisibility of this intermediate unit, one also speaks of transparency.
Caches can take the form of a hardware structure (for example, main memory chips) or a software structure (for example, temporary files or reserved memory space).
In practice, the cache is a mirrored resource that is processed / used very quickly as a substitute for the original.