servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

This line of code sets the IP address of the server socket to INADDR_ANY, which means that the socket will accept connections on all available network interfaces of the machine. htonl() is used to convert the IP address from host byte order to network byte order. This is necessary because network addresses are represented in big-endian byte order, while most modern computers use little-endian byte order.