How can understanding and implementing best practices related to PHP security, such as handling global variables, prevent potential issues in PHP scripts?

Understanding and implementing best practices related to PHP security, such as properly handling global variables, can prevent potential security vulnerabilities in PHP scripts. By sanitizing and validating user input, avoiding the use of global variables whenever possible, and using secure coding practices, developers can reduce the risk of attacks such as SQL injection and cross-site scripting.

// Example of how to properly handle global variables in PHP
function get_input($input_name) {
    if(isset($_POST[$input_name])) {
        return sanitize_input($_POST[$input_name]);
    } else {
        return null;
    }
}

function sanitize_input($input) {
    // Implement your sanitization logic here
    return htmlspecialchars($input);
}

$username = get_input('username');
$email = get_input('email');