What potential issues can arise when trying to display external content using PHP?

One potential issue when displaying external content using PHP is the risk of Cross-Site Scripting (XSS) attacks if the external content is not properly sanitized. To prevent this, always sanitize and validate any external content before displaying it on your website. This can be done by using functions like htmlentities() or htmlspecialchars() to escape special characters.

// Example of sanitizing external content before displaying it
$externalContent = "<script>alert('XSS attack!')</script>";
$sanitizedContent = htmlspecialchars($externalContent);
echo $sanitizedContent;