ICS or Internet Connection Sharing is a tool used in Windows to share your internet conection be it Wifi or Lan.   To set up the conection you will need the following:

Ethernet Cord
Laptop or Desktop running Windows 7
Administrative Rights on that computer

Now for the steps.

1. Open Network and Sharing center
           To do this open your start menu and search Network and Sharing
2. Click Wireless Network Connection (Your Router Name Here)
3. When the dialog box opens click Properties
4. Then in the sub-menu click the tab Sharing
5. Check the box that says (Allow other Network users to connect to this computer's Internet connection.
6. Press OK and close all open windows.
7. If you are using a laptop make sure it is plugged in then plug the Ethernet cable into the slot on you computer.
8. Turn the other computer on and there you go.

Note- This also allows you to connect your Xbox 360 or any other device with an Ethernet Connection slot to the Internet.   Also please make sure you disable your Windows Firewall I always seem to have a connection problem when it is enabled because it tries to block the other devices.
 
TCP/IP

TCP/IP or Transmission Control Protocol(TCP) and Internet Protocol(IP) is an addressing system needed to deliver packets of information to your computer.   All computers that connect to a network has to have a TCP/IP address or IP address for short.   Data is broken up into small packets of information and the addresses of borth the reciving and sending computer is attached to each packet.   It like mailing a letter to your friend you have to have a sending address and the address it is going too, but not all people put there address also known as the return address on the letter in computer terms this can be called a Proxy.   It would be nearly impossible to trace the letter or information back to you, now I am not saying it is imposible with some of the technology we have these days.  

An IP address contains for sets of number followed by periods

Example-

201.46.197.112

Each part of the address directs the packet of data along its way, almost like an address

Example-

201. indicates the state you computer is in

46. indicates the city

197. indicates the street or building you computer is in

112. indicates the computer you are using

As you can tell, it is like an address

Example-

Washington

Seattle

1711 DC Dr.

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