What is the significance of using htmlspecialchars function in PHP when displaying user input data in forms?

When displaying user input data in forms, it is important to use the htmlspecialchars function in PHP to prevent cross-site scripting (XSS) attacks. This function converts special characters like < and > into their HTML entities, ensuring that any malicious scripts embedded in the input data will not be executed when the form is rendered on the page.

// Displaying user input data in a form using htmlspecialchars
$userInput = $_POST['user_input']; // Assuming user input is retrieved from a form submission

echo '<input type="text" name="user_input" value="' . htmlspecialchars($userInput) . '">';