What does the symbol & mean in a variable to a function?

Question

PHP

Friends, what does the "&" symbol show before a variable in a function?

function dodo(&$comments) {

}

Thanks in advance.

Answer 1

php.net/manual/en/language.references.whatdo.php
php.net/manual/en/language.references.pass.php

Answer 2

Passing a reference to a variable. The function works with the data passed to it directly, and not with a copy.