PHP Registration Form using GET, POST Methods with Example

By : Fiona Brown Fiona Brown
Hours Updated

⚡ Smart Summary

Forms Handling in PHP captures user input from HTML forms and processes it on the server through the $_POST and $_GET superglobals. This walkthrough builds a registration form, explains the POST and GET methods, compares them, and shows how to process fields, checkboxes, and search input.

  • 📝 What Forms Do: An HTML form collects user input through fields like text boxes, checkboxes, and buttons, then submits it to a server script.
  • 📬 POST Method: $_POST sends values in the HTTP body, keeping them out of the URL, which suits logins and sensitive data.
  • 🔗 GET Method: $_GET appends values to the URL, so results can be bookmarked, which is ideal for search forms.
  • ⚖️ POST vs GET: POST has no practical length limit and supports many data types; GET is shorter, string only, and visible.
  • ✅ Processing Input: The isset() function checks whether a field was submitted before the script reads and uses its value.
  • ☑️ Checkboxes: A checkbox sends a value only when ticked, so isset() confirms whether the user agreed or selected the option.
  • 🤖 AI Assist: AI tools can generate a validated, secure form and help diagnose why a form is not submitting correctly.
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PHP Forms Handling

What is Form?

When you log in to a website or into your mailbox, you are interacting with a form.

Forms are used to get input from the user and submit it to the web server for processing.

The diagram below illustrates the form handling process.

PHP Form

A form is an HTML tag that contains graphical user interface items such as input boxes, check boxes, radio buttons, and more.

The form is defined using the <form>…</form> tags, and GUI items are defined using form elements such as input.

When and why we are using forms?

  • Forms come in handy when developing flexible and dynamic applications that accept user input.
  • Forms can be used to edit already existing data from the database.

Create a form

We will use HTML tags to create a form. Below is the minimal list of things you need to create a form.

  • Opening and closing form tags <form>…</form>
  • Form submission type POST or GET
  • Submission URL that will process the submitted data
  • Input fields such as input boxes, text areas, buttons, checkboxes, and similar.

The code below creates a simple registration form.

<html>
<head>
<title>Registration Form</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>

<h2>Registration Form</h2>

<form action="registration_form.php" method="POST"> First name:

<input type="text" name="firstname"> <br> Last name:

<input type="text" name="lastname">

<input type="hidden" name="form_submitted" value="1" />

<input type="submit" value="Submit">

</form>
</body>
</html>

Viewing the above code in a web browser displays the following form.

Create a form

HERE,

  • <form…>…</form> are the opening and closing form tags
  • action=”registration_form.php” method=”POST” specifies the destination URL and the submission type.
  • First/Last name: are labels for the input boxes
  • <input type=”text”…> are input box tags
  • <br> is the new line tag
  • <input type=”hidden” name=”form_submitted” value=”1″/> is a hidden value that is used to check whether the form has been submitted or not
  • <input type=”submit” value=”Submit”> is the button that, when clicked, submits the form to the server for processing

Submitting the form data to the server

The action attribute of the form specifies the submission URL that processes the data. The method attribute specifies the submission type.

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PHP POST method

  • This is the built-in PHP superglobal array variable that is used to get values submitted via the HTTP POST method.
  • The array variable can be accessed from any script in the program; it has a global scope.
  • This method is ideal when you do not want to display the form post values in the URL.
  • A good example of using the POST method is when submitting login details to the server.

It has the following syntax.

<?php
$_POST['variable_name'];
?>

HERE,

  • “$_POST[…]” is the PHP array
  • “‘variable_name'” is the form field name.

PHP GET method

  • This is the built-in PHP superglobal array variable that is used to get values submitted via the HTTP GET method.
  • The array variable can be accessed from any script in the program; it has a global scope.
  • This method displays the form values in the URL.
  • It is ideal for search engine forms as it allows users to bookmark the results.

It has the following syntax.

<?php
$_GET['variable_name'];
?>

HERE,

  • “$_GET[…]” is the PHP array
  • “‘variable_name'” is the URL variable name.

GET vs POST Methods

POST GET
Values not visible in the URL Values visible in the URL
Has no limitation on the length of the values since they are submitted via the body of the HTTP request Has a limitation on the length of the values, usually 255 characters. This is because the values are displayed in the URL. Note the upper limit of the characters is dependent on the browser.
Has lower performance compared to the GET method due to time spent encapsulating the POST values in the HTTP body Has higher performance compared to the POST method due to the simple nature of appending the values in the URL.
Supports many different data types such as string, numeric, binary, and more. Supports only string data types because the values are displayed in the URL
Results cannot be bookmarked Results can be bookmarked due to the visibility of the values in the URL

The diagram below shows the difference between GET and POST.

GET vs POST Methods

GET vs POST Methods

Processing the registration form data

The registration form submits data to itself as specified in the action attribute of the form.

When a form has been submitted, the values are populated in the $_POST superglobal array.

We will use the PHP isset function to check if the form values have been filled in the $_POST array and process the data.

We will modify the registration form to include the PHP code that processes the data. Below is the modified code.

<html>
<head>
<title>Registration Form</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

</head>
<body>

<?php if (isset($_POST['form_submitted'])): ?> // this code is executed when the form is submitted

<h2>Thank You <?php echo $_POST['firstname']; ?> </h2>

<p>You have been registered as
<?php echo $_POST['firstname'] . ' ' . $_POST['lastname']; ?>
</p>

<p>Go <a href="/registration_form.php">back</a> to the form</p>

<?php else: ?>

<h2>Registration Form</h2>

<form action="registration_form.php" method="POST">

First name:
<input type="text" name="firstname">

<br> Last name:
<input type="text" name="lastname">

<input type="hidden" name="form_submitted" value="1" />

<input type="submit" value="Submit">

</form>

<?php endif; ?>
</body>
</html>

HERE,

  • <?php if (isset($_POST[‘form_submitted’])): ?> checks if the form_submitted hidden field has been filled in the $_POST[] array and displays a thank you and first name message. If the form_submitted field has not been filled in the $_POST[] array, the form is displayed.

More examples

Simple search engine

We will design a simple search engine that uses the PHP GET method as the form submission type.

For simplicity’s sake, we will use a PHP if statement to determine the output.

We will use the same HTML code for the registration form above and make minimal modifications to it.

<html>
<head>
<title>Simple Search Engine</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>

<?php if (isset($_GET['form_submitted'])): ?>

<h2>Search Results For <?php echo $_GET['search_term']; ?> </h2>
<?php if ($_GET['search_term'] == "GET"): ?>

<p>The GET method displays its values in the URL</p>

<?php else: ?>
<p>Sorry, no matches found for your search term</p>

<?php endif; ?>

<p>Go <a href="/search_engine.php">back</a> to the form</p>

<?php else: ?>

<h2>Simple Search Engine - Type in GET </h2>

<form action="search_engine.php" method="GET">

Search Term:
<input type="text" name="search_term">
<br>

<input type="hidden" name="form_submitted" value="1" />

<input type="submit" value="Submit">

</form>
<?php endif; ?>
</body>
</html>

View the above page in a web browser.

The following form will be shown.

Simple Search Engine

Type GET in upper case letters, then click on the submit button.

The following will be shown.

Simple Search Engine

The diagram below shows the URL for the above results.

Simple Search Engine

Note the URL has displayed the value of search_term and form_submitted. Try to enter anything different from GET, then click on the submit button and see what results you get.

Working with check boxes, radio buttons

If the user does not select a check box or radio button, no value is submitted. If the user selects a check box or radio button, the value one (1) or true is submitted.

We will modify the registration form code and include a check button that allows the user to agree to the terms of service.

<html>
<head>
<title>Registration Form</title>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<?php if (isset($_POST['form_submitted'])): ?>
<?php if (!isset($_POST['agree'])): ?>
<p>You have not accepted our terms of service</p>
<?php else: ?>
<h2>Thank You <?php echo $_POST['firstname']; ?></h2>
<p>You have been registered as
<?php echo $_POST['firstname'] . ' ' . $_POST['lastname']; ?>
</p>
<p> Go <a href="/registration_form2.php">back</a> to the form</p>
<?php endif; ?>
<?php else: ?>
<h2>Registration Form</h2>
<form action="registration_form2.php" method="POST">
First name:
<input type="text" name="firstname">
<br> Last name:
<input type="text" name="lastname">
<br> Agree to Terms of Service:
<input type="checkbox" name="agree">
<br>
<input type="hidden" name="form_submitted" value="1" />
<input type="submit" value="Submit">
</form>
<?php endif; ?>
</body>
</html>

View the above form in a browser.

Working with Check boxes, Radio buttons

Fill in the first and last names.

Note the Agree to Terms of Service checkbox has not been selected.

Click on the submit button.

You will get the following results.

Working with Check boxes, Radio buttons

Click on the back to the form link, then select the checkbox.

Working with Check boxes, Radio buttons

Click on the submit button.

You will get the following results.

Working with Check boxes, Radio buttons

FAQs

$_GET reads values from the URL query string, $_POST reads values from the request body, and $_REQUEST merges GET, POST, and cookie data. Prefer the specific array so you know exactly where a value came from.

Never trust raw input. Validate with filter_var() or rules for each field, and escape output with htmlspecialchars() to stop XSS. Use prepared statements for database writes to prevent SQL injection.

Common causes are a form method of GET instead of POST, missing name attributes on inputs, a wrong action URL, or a missing multipart enctype for file uploads. Check each of these against your form.

Yes. AI can build the HTML form plus server-side validation, CSRF protection, and escaped output. Review the rules for each field and confirm the security checks match your application before deploying.

Yes. Share the form and handler, and AI can spot a method mismatch, a missing name attribute, an incorrect action path, or a validation branch that blocks submission, then suggest the fix.

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