The require() and require_once() functions perform same work. Both functions will include and evaluates the specific file while executing the code.
if include() is not able to find a specified file on location at that time it will throw a warning however, it will not stop script execution. For the same scenerio require() will throw fatal error and it will stop the script execution.
Example
<?php
echo “Hello”;
?>
test.php
<?php
require(‘echo.php’);
require_once(‘echo.php’);
?>
test.php outputs: “Hello”.
