WHAT IS THE INTERNET

 The Internet is a massive public spiderweb of computer connections. It connects personal computers, mainframes, cell phones, GPS units, music players, soda pop machines, car alarms, and even dog collars. All of these computer connections exist for the sake of free information sharing.

WHAT ARE PROTOCOLS

A 'protocol' is a set of invisible computer rules that govern how an internet document gets transmitted to your screen. These dozens of programmatic rules work in the background in the same way a bank employs staff procedures to keep your money safe.

WHAT IS TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol)

TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP.
TCP/IP is a two-layer program. The higher layer, Transmission Control Protocol, manages the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer, Internet Protocol, handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they'll be reassembled at the destination.

TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer. TCP/IP and the higher-level applications that use it are collectively said to be "stateless" because each client request is considered a new request unrelated to any previous one (unlike ordinary phone conversations that require a dedicated connection for the call duration). Being stateless frees network paths so that everyone can use them continuously. (Note that the TCP layer itself is not stateless as far as any one message is concerned. Its connection remains in place until all packets in a message have been received.)

HOW DOES INFORMATION TRAVEL THROUGH THE INTERNET

Data is divided up into packets
Data routes across the Internet can be switched to avoid congestion
Entire mechanism is handled by the TCP/IP protocols

The Internet is based on packet-switched protocols. Information is carried in packets, which can be imagined as small parcels being passed from computer to computer. Large chunks of data are usually broken up into several smaller packets before being sent through the network. The delivery mechanism, or protocol, that is used to encode the packet ensures safe transit, and provides a way of reconstructing the data when it reaches its destination. The protocols used on the Internet are referred to as TCP/IP, standing for Transmission Control Protocol / Internet Protocol.
As a switched network, the physical connections between computers do not matter as far as Internet traffic is concerned — the protocols ensure that guaranteed information delivery is more important than speed or use of a particular route. This means that a sequence of packets might arrive out of order, with some travelling through the net by a faster, shorter route than others. TCP/IP provides the means for your software to piece together those packets into meaningful data. The ability to take different routes through the network is a fundamental part of the original design of TCP/IP, as it allows the Internet to route around damaged areas of the network.

HOW DOES THE CONNECTION WORK FROM HOME

To connect from home you need several things. Apart from a computer (obviously!) you'll need a phone connection, a modem or ADSL router, and some Internet software. Things will be easier if you're using a relatively recent operation system, such as Windows Vista/XP or MacOSX, but it's possible to connect with older or more obscure systems.
With a modem and the appropriate software, you can dial up another modem connected to another computer, and establish a network connection with it. Usually, this computer is linked into the Internet, and so you're online.
With an ADSL modem or router, a similar procedure happens, but a filter splits the telephone line into voice and data (low and high frequencies) and your router negotiates a connection with the ADSL equipment in the telephone exchange.