Understanding the code structure

Question

What means and what will do this piece of code?

(function ($) {}(jQuery));

1. What is relation between "$" and "jQuery".
2. Do brackets "(", ")" on edges of code has any function? Do they do something?

Answer 1

(function ($) {}(jQuery));

jQuery is existing jQuery object , $ is same jQuery object within Immediately-Invoked Function Expression (IIFE) statement {}

Do brackets "(", ")" on edges of code has any function? Do they do something?

Yes. Comma , separates arguments to function

e.g.,

(function($, $$) {
  // `$`:`{"abc":123}` ; `$$`:`{"def":456}`
  console.log($["abc"], $$["def"]) // `123` , `456`
 // set `$` within IIFE to object `{"abc":123}` ,
 // set `$$` to object `{"def":456}`
}({"abc":123}, {"def":456})); 

Answer 2

What is relation between "$" and "jQuery"?

$ is shorthand for jQuery. Sometimes $ is disabled as it may conflict with other Javascript libraries you are using. It is otherwise identical.

and refer this

http://api.jquery.com/jQuery.noConflict/