What are the key differences between UDP and TCP connections in PHP?

UDP (User Datagram Protocol) is a connectionless protocol that does not guarantee delivery of data packets, while TCP (Transmission Control Protocol) is a connection-oriented protocol that ensures reliable data transmission. In PHP, you can create UDP connections using functions like `socket_create()` and `socket_sendto()`, while TCP connections can be established with functions like `fsockopen()` and `fwrite()`. When choosing between UDP and TCP connections in PHP, consider factors such as the importance of data reliability and the specific requirements of your application.

// Example of creating a UDP connection in PHP
$socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
socket_sendto($socket, $data, strlen($data), 0, $host, $port);
socket_close($socket);