This post is a part of an unfinished Appendix from a series of articles on introducing 10-year-olds to programming with the goal of making a simple Minecraft mod.

Before we can talk about the multi-player games, servers, and the internet in general, we need to understand a bit about networks. A network is a group of computers connected together that can "talk" to each other. A very simple network could be two computers connected by a network cable or two Nintendo DSes sharing a game wirelessly.

In most homes today, a lot of electronic devices (computers, laptops, printers, iPhones, DSes, etc.) are connected to a wireless network (also called WiFi). The piece of equipment that provides this network is usually a router or hub. Since routers are more common and multi-purpose, we're going to assume you have one for this article :)

IP Addresses

Just like your friends have a phone number you use to call or text them, computers have IP addresses. When a computer joins a network, an input/output hardware device (i.e. network card or USB network adaptor) receives a unique IP address from the router. An example of an IP address on your home network could be 192.168.0.42.

Machine Names

Sometimes we don't need to remember our friends' phone numbers; home and cell phones often have a built-in address book so you can choose someone by name and the phone automatically knows which number to use. Similarly, computers on a network can be identified by name instead of IP address. A special computer program or server called a name server translates a machine name into an address. For instance, I name a lot of my machines after Transformers - the one I'm writing this article on is called 'skyfire'.

Further Reading