Each computing device is allocated an address that consists of a group of four numbers(IPv4) or six numbers (IPv6)
Each number is between 0 and 255, and are displayed as 192.168.0.0 or 192.168.255.255
All computing devices on the same network will have a unique address, and the network will also have a router or a hub that controls communication between the devices. A router will also be used to connect the home or office network to the Internet service provider (ISP) that provides the connection to the rest of the Internet.
If you connect using public wifi then that wifi node connects to a router that connects to an ISP.
Data over a mobile phone connects via the phone cell tower to the router of the phone company acting as an ISP.
The ISPs have routers that connect to each other, and to other routers that form the backbone of the Internet, connecting via optical fibre or satellite link to other routers in other parts of the world.
Each of these routers and servers that are accessible directly through the Internet has a unique IPv4 or IPv6 address. Each address is recorded in databases held by the Domain Name System (DNS)
Many of these IP addresses are also linked to registers of human readable names such as open.ac.uk or google.com
The domain name does not tell you where a domain is hosted - where the server physically exists
The domain name registers may also include the name of the owner of that domain and the geographic location of the server that hosts that domain. We can look up the IP address, or the domain name to discover this information.