42.zip - Zip Bomb!

I was reading online sometime back and I came across this really interesting thing called 42.zip also known as Zip Bomb, Zip of Death, Peta bomb or decompression bomb.

The file is only 42,374 bytes (42KB). When unzipped it becomes 4,503,599,626,321,920 bytes (4.5 Peta Bytes)!!!

The main use of it is to render useless the host reading the file, usually to disable antivirus. When you unzip it, the antivirus will be busy scanning the unzipped files, sucking up all the available resources and a malicious program injected can execute itself undetected!

How it works?
42.zip has 16 zipped files.
Each of these 16 have 16 zipped files.
Each of these have 16 zipped files.
Each of these have 16 zipped files.
Each of these have 16 zipped files.
Each of these have 1 file, with the size 4.3GB

Still. How is this level of compression achieved??
It relies on repetition of identical files!! Think of it as same file being unzipped over and over again.
Awesome isn't it?!

Also read Fork Bomb.