PHP & The Web›Core· 45 min read

Handling Forms ($_POST & $_GET)

The heart of PHP: receive data from HTML forms and respond. This is where dynamic sites begin.

What you will learn

Receive form data with $POST and $GET
Connect an HTML form to a PHP script
Display submitted data

Form → PHP

An HTML form’s action points to a PHP file, and method decides how the data arrives: POST → $_POST, GET → $_GET. Each field’s name becomes the array key. ($_POST and $_GET are special built-in arrays — called *superglobals* — that PHP fills in for you with the submitted data.)

Here is the whole journey, start to finish, so you can picture how a click in the browser ends up as data in PHP:

The user fills in the form fields and clicks the submit button.
The browser bundles up each field by its name and sends them to the file in action (here submit.php).
Because method="post", PHP places those values into the $_POST array, keyed by each field’s name.
submit.php runs, reads the values out of $_POST, and builds an HTML response.
The server sends that HTML back, and the browser shows the result to the user.

First, the HTML form. Each input has a name — that name is the label PHP will use to find the value later:

The HTML form

<!-- index.html (or .php) -->
<form action="submit.php" method="post">
  <input type="text" name="username">
  <input type="email" name="email">
  <button type="submit">Send</button>
</form>

The action="submit.php" says where to send the data, and method="post" says to send it hidden in the request body. The two inputs are named username and email — keep those names in mind, because the PHP file uses them as keys.

Now the PHP file that receives it. It pulls each value out of $_POST using the matching field name:

submit.php reads the form data

<!-- submit.php -->
<?php
  $name = $_POST["username"];
  $email = $_POST["email"];
  echo "Thank you, $name! We will email $email.";
?>

$_POST["username"] grabs whatever the user typed in the field named username and stores it in $name; the email line does the same. The echo then builds a friendly reply using those values.

Note: Output (if the user typed "Asha" and "asha@x.com"): Thank you, Asha! We will email asha@x.com. The key inside $_POST[...] matched the form field’s name exactly, so PHP found the right value. Change the field name without changing the PHP key and it would break.

Watch out: The $_POST key must exactly match the form field’s name attribute. name="username" → $_POST["username"]. A mismatch gives an “undefined index” warning.

Tip: Recall from the HTML course: use POST for logins and anything sensitive (data hidden in the request body), and GET for searches (data visible in the URL).

Q. A form field named "email" submitted with POST is read in PHP as:

Answer: With method="post", fields arrive in $POST keyed by their name attribute: $POST["email"].

✍️ Practice

Build an HTML form that posts to a PHP file which greets the user by name.
Add an email field and display both values.

🏠 Homework

Build a contact form (name, email, message) where the PHP page confirms the submission.