Forms & User Input · Lesson 1 of 6

HTML Forms with PHP

Connect an HTML form to a PHP request handler safely.

Lesson

An HTML form sends named fields to a server endpoint. The handler must treat every submitted value as untrusted: validate its type and meaning, enforce a request method, and escape values when rendering them back into HTML. Use CSRF protection for state-changing forms in production applications. This minimal example reads one field only after confirming that it is a string. Further guidance Treat every submitted field and uploaded file as untrusted. Validate type, length, allowed values, and request method on the server; use CSRF protection for state changes. Escape values for their output context, and never use browser validation as the only safeguard. Practice task: Create a fresh example for HTML Forms with PHP. Predict the result before running it, then change one input and explain why the result changes. Test a normal case and one boundary or invalid case where it applies. Compare your output with the example and note one rule you would use in a real project.

Code examples

HTML Forms with PHP

PHP

$name = $_POST['name'] ?? '';
if (is_string($name)) {
    echo htmlspecialchars(trim($name), ENT_QUOTES, 'UTF-8');
}

Expected output

Escaped submitted name

Key points

Connect an HTML form to a PHP request handler safely.
Validate input on the server before processing it.
Escape output for its context and protect state-changing forms from CSRF.

Your learning progress

Finish this lesson

Optional practice

PHP playground

This site does not execute learner-provided PHP code. Connect a secured PHP sandbox service before enabling code execution.

Execution is disabled. No code is sent to a server.