Cache memory
Eoin is absolutely right! Caching only means storing data from your extra memory or hard drive (database, files, etc.) into primary memory or application memory. This speeds up execution because reading from App Mem is faster than reading from disks. Therefore, if we say that a file is stored in a cache, you can read it faster than if it weren't, and you should have read it from disk.
For more details on caching in asp.net see link
A general idea about cache memory can be found here
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Ok (and this is completely simplified)
Classes (i.e. reference types) are stored on the heap with a pointer to that reference type stored on this stack.
Structures / Simple types (i.e. value types) are stored directly on the stack.
But from a caching perspective, the idea is that the stored value is stored in the full memory of the application.
The benefit would be that if you have some value that you regularly use that is stored in the database, then you can retrieve it once, put it in the cache and retrieve it directly from memory on each subsequent use rather than having to go back to your database (or filesystem or other slow search facility)
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