What is the significance of naming conventions in HTML form elements when handling POST data in PHP?

When handling POST data in PHP, naming conventions in HTML form elements are significant because they determine how the data is passed to the server. By giving form elements unique and descriptive names, you can easily access the submitted data in PHP using the $_POST superglobal array. It is important to ensure that the names of form elements are consistent and meaningful to avoid confusion when processing the data.

<form method="post" action="process_form.php">
    <input type="text" name="username" placeholder="Enter your username">
    <input type="password" name="password" placeholder="Enter your password">
    <button type="submit">Submit</button>
</form>
```

In the PHP script (process_form.php) that handles the form submission:

```php
$username = $_POST['username'];
$password = $_POST['password'];

// Process the submitted data