Why is htmlspecialchars() important for displaying data in PHP applications, and what role does it play in preventing security vulnerabilities?

htmlspecialchars() is important for displaying data in PHP applications because it helps prevent security vulnerabilities such as Cross-Site Scripting (XSS) attacks. This function converts special characters like < and > into their HTML entities, which ensures that user input is not interpreted as HTML code by the browser. By using htmlspecialchars(), you can safely display user input on a webpage without risking malicious code execution.

// Display user input safely using htmlspecialchars()
$user_input = "<script>alert('XSS attack!');</script>";
echo htmlspecialchars($user_input);