How can the use of htmlspecialchars() function improve security when inserting values into HTML code in PHP?

When inserting values into HTML code in PHP, it is important to properly sanitize the input to prevent XSS (Cross-Site Scripting) attacks. Using the htmlspecialchars() function in PHP can help improve security by converting special characters like <, >, ", ', and & into their respective HTML entities, preventing them from being interpreted as code.

$value = "<script>alert('XSS attack!');</script>";
echo htmlspecialchars($value, ENT_QUOTES, 'UTF-8');