If a .zip file contains all of the information of the original, just in less space, why does it have to be unzipped to access any of it?

Question

If a .zip file contains all of the information of the original, just in less space, why does it have to be unzipped to access any of it?

In: 1276

Answer 1

Others have explained how zip can work.

But just as an alternative, you don’t have to zip something to compress it. Several file systems can natively store data compressed and the access layer transparently decompresses it when you read it.

Windows NTFS is one of these, you can right click a file and set it to compressed. The size on disk and the actual size would then differ, but you’re still perfectly able to read it, albeit slower.

On certain (slow) disks this might actually speed up file reads – the disk IO is much slower than the CPU, so you read less but get more.