What are the best practices for organizing and structuring PHP code for form processing tasks?

When organizing and structuring PHP code for form processing tasks, it is important to separate the logic into different files or functions for better readability and maintainability. One common practice is to have a separate file for form validation, another for form submission handling, and another for displaying the form itself. This helps keep the code modular and easier to debug.

// form_validation.php
function validateForm($formData) {
    // validation logic here
}

// form_submission.php
function processForm($formData) {
    // form submission logic here
}

// display_form.php
function displayForm() {
    // form HTML code here
}