What are common differences between running PHP scripts on a home server versus an online server like 1&1?

When running PHP scripts on a home server, you may encounter differences in server configurations such as PHP versions, extensions, and settings compared to online servers like 1&1. To ensure compatibility and consistent behavior, it's important to check and adjust your scripts accordingly.

// Example code snippet to check PHP version and display it
echo 'PHP version: ' . phpversion();