Client (browser) software sends its request for data to the host, where the web server software processes the request.
A computer with a single IP address can host several types of servers. This means the address might require a port number to identify the correct server if it is not the IP's default server. Each port is associated with a particular server. Ports are identified by a number from 0 to 65,535, but common server types, such as FTP servers, are given the same number by convention.
The host computer must have a unique IP address to send and receive information across the Internet. Because raw IP addresses are very intimidating, they are assigned a unique domain name, which is less daunting. The domain name is part of a hierarchical lookup system called the Domain Name System (DNS).