To set constant using `define()` will not work with `namespace` unlike using `const`.
Example:
<?php
namespace MyProject;
const IS_IT_CONNECTED = true; // will be able to access via `\MyProject\IS_IT_CONNECTED`
define('START_TIME', time());// will be able to access via `START_TIME` only, not be able to access via ---`\MyProject\START_TIME`---
?>
Call:
<?php
var_dump(\MyProject\IS_IT_CONNECTED);// true
var_dump(START_TIME);// numbers
var_dump(\MyProject\START_TIME);// Fatal error: Uncaught Error: Undefined constant...
?>