What are best practices for ensuring that PHP scripts handle form submissions accurately and efficiently, especially when integrating external scripts like jQuery?

When handling form submissions in PHP scripts, it is important to properly sanitize and validate user input to prevent security vulnerabilities such as SQL injection or cross-site scripting attacks. Additionally, using server-side validation in addition to client-side validation with tools like jQuery can help ensure data accuracy. Finally, efficiently processing form submissions by organizing code into separate functions and utilizing AJAX for asynchronous form submission can improve performance.

<?php
// Sanitize and validate form input
$name = filter_var($_POST['name'], FILTER_SANITIZE_STRING);
$email = filter_var($_POST['email'], FILTER_VALIDATE_EMAIL);

// Server-side validation
if (empty($name) || empty($email)) {
    echo "Please fill out all required fields.";
} else {
    // Process form submission
    // Insert data into database, send email, etc.
    echo "Form submitted successfully!";
}
?>