PHP Constants Tutorial
A constant value cannot be changed.It is an identifier for a simple value. During the script.Constants a constant value becames global and can be used outside of the entire script.
A constant is case-sensitive. By convention, constant identifiers are always uppercase.Constants can not change during the script.A constant name can not start with $.
PHP Constants Syntax
<?php define('Const Name', 'value'); ?>
PHP Constants Example
<?php define("hello", "World"); echo hello; ?>