How difficult is it for someone with HTML knowledge to learn PHP, and what are some potential challenges they may face?

Learning PHP for someone with HTML knowledge can be manageable, as both languages share similar syntax and concepts. However, PHP introduces new concepts such as variables, data types, functions, and control structures that may pose challenges. It is important to practice writing PHP code regularly and familiarize oneself with PHP-specific functions and features to overcome these obstacles.

<?php
// Example PHP code snippet
$variable = "Hello, World!";
echo $variable;
?>