System freezing reason?

Question

Typing this :(){:|:&};: will cause system freeze.What is the reason behind this.

Answer 1

:()

defines a function called ':'

{ :|:& };

This is the function: It calls the function itself and pipes the output to the same function ":" and puts the process in the background. (Recursive invocation) with ; it ends the function definition

:

Calls the function and creates havoc.

Answer 2

This was answered on stackoverflow.com. You'll find detailed answers over there.