What is "associative-array"

Associative array is one that allows assigning a name to an array key.

The array PHP, for example, allows the association of indexes with specific names. In this case, it becomes similar to the hash of ruby or an object of javascript.

Example of array common:

$array = array(
   1,
   2,
   3
);

Example of array associative:

 $array = array(
    'nome' => 'Stack Overflow', // Índice associativo
    1, 
    2,
    3
 );