Can I ask question about "caching" in IPFS?

Recently, I saw the post https://stackoverflow.com/questions/47450007/where-does-ipfs-store-all-the-data
and read some sentence "If you get data, you cache it so...".

So here is my question.

Is IPFS caching means, store all chunks of "data" in hard disk?
If so, when you get large files like 5.5G media file, you store every piece of data at some time? (Does it mean full copy though? copy all chunks of data) 

Thanks for reading.