When Function[body] or body& is applied to a set of arguments, # (or #1) is replaced by the first argument, #2 by the second, and so on. #0 is replaced by the function itself.
If there are more arguments supplied than #i in the function, the remaining arguments are ignored. »
## stands for the sequence of all arguments supplied. »
Function has attribute HoldAll. The function body is evaluated only after the formal parameters have been replaced by arguments.
The named formal parameters xi in Function[{x1, ...}, body] are treated as local, and are renamed xi$ when necessary to avoid confusion with actual arguments supplied to the function. »
Function constructs can be nested in any way. Each is treated as a scoping construct, with named inner variables being renamed if necessary. »
Function[params, body, {attr1, attr2, ...}] represents a pure function that is to be treated as having attributes attri for the purpose of evaluation. »
in LISP or formal logic. 
EXAMPLES
Basic Examples 
Scope 