How to add to an array in php?

Question

PHP

Guys. Hello.
How many on the Internet did not climb. So I can't find a better answer.
There is an array. Example from php.su
$A["Ivanov"] = array("name"=>"Ivanov II", "age"=>"25", "email"=>"[email protected]") ;
How can I make it so that I can supplement this array with the date of birth or anything else. By button?

Answer 1

$A["Ivanov"]['birthday'] = '17.03.1989';