Anonymous functions, is a function that allows the creation of a function without any specific name. We can use it as follows:

1-Assign it to a variable, then call it later using the variable's name.
2-We can store an array of different anonymous functions in a single array.
3-Pass the anonymous function to another function that can be used later generally known as a callback.
4-The body of anonymous function is ended with a semicolon.

1- Assigning variable:

$anonymous = function( $name) {
  return ( "Hello, $name!" );
};

After assignment we can call the function using the variable name

$anonymous(John);

OUTPUT: Hello John!

2- Storing anonymous functions in an array:

$anonymous =array(

function() {
  echo "Hello, first function called!" ;die;
},


function() {
  echo "Hello,  second function called!" ;die;
},


function() {
  echo "Hello,  third function called!" ;die;
},

function() {
  echo "Hello,  fourth function called!" ;die;
}

);

$order = rand( 0, 3 );
$anonymous[$order]();

Random OUTPUT: 

Hello,  fourth function called!
Hello,  first function called!
Hello,  third function called!

3-Passing an anonymous function as a callback:

$anonymous = function( $name) {
  echo "Hello, $name! </br>";
};

$list = array('John','Ravi','Jayant','Surit','Rakesh');

$listing = array_walk($list, $anonymous);

OUTPUT: 

Array
(
    [0] => Hello, John!
    [1] => Hello, Ravi!
    [2] => Hello, Jayant!
    [3] => Hello, Surit!
    [4] => Hello, Rakesh!
)