Character
A character is a unit of information, that represents represents letters, punctuation signs, ideogram, etc.
Characters may be represented as a byte, on 8 bits, but also on longer sequences, with UTF-8 or UTF-16. By default, PHP uses 8 bits, and there are several extensions to manipulate the encodings.
There is no dedicated type for characters: a string of one element is used for that purpose. There are some special constraints related to manipulating characters inside a string: it is possible to access individual character in a string, with the array syntax, both to read or modify them.
<?php
$string = 'abc';
echo $string[1]; // display b
var_dump($string[1]);
//string(1) b
?>