Difference between $() and $(document).ready()

Question

What's the difference between :

$(function() { ... });  

and

$(document).ready(function() { ... });  

and what mean this $() ?

Answer 1

As stated in the docs http://api.jquery.com/ready/

$( document ).ready(function() {
  // Handler for .ready() called.
});

Which is equivalent to calling:

$(function() {
  // Handler for .ready() called.
});

---

$ is just a variable name / shortcut for jQuery

so you're basically calling the function jQuery() and passing some parameters to it or calling it's methods

Answer 2

There is no difference between the two, the first one is the alias for the second one.