The Internet Protocol Suite, also known as the TCP/IP model, provides end-to-end communication specifying how data should be formatted and transmitted. To understand this better, one must first know a bit more about layer-based communications.
Communication on the Internet is based on the principle of layer-based traffic. Each layer receives information from the layer above it and wraps what is known as a header around this packet of data. Fundamentally, each layer should not care what type of data is being sent through it.
It might be easier to think about it as a if you are work for a company that receives a great deal of mail. To send a letter to another someone at another company I give the letter to the mail facility at my office. From there, they would put on their stamp and send it through the mail to the other company. The whole process would reverse itself on the other end so that the recipient gets the letter.
Essentially, once I put a valid address on the envelope, I no longer have to worry about how it gets there, the lower levels will take care of it. I just wait for the response. Just the same, the post office does not need to worry about the content of what is being sent.
Because of the complexity of the Internet in general, it is common for packets of data to get lost or mis-transmitted. It is because of this that sending large streams of data can be difficult. The TCP protocol provides a link-to-link communication. In this protocol, each link will send acknowledgement packets that data has been received. In this way, the small packets that make up a TCP transmission can be resent very quickly without any notice on the user’s end.
The IP layer is the main addressing layer. It is how each device on the Internet can address any other device. Currently in IPv4 there can be 4,294,967,296 distinct addresses on the internet (with some tricks by ISPs and WANs, this can be stretched to meet current demands). IPv4 was developed in 1981 and it was never imagined that we would ever run into a shortage. We have. IPv6 is currently being introduced in hardware and operating systems to deal with the shortage. IPv6 has space for 2^128 addresses instead of IPv4’s 2^32.
Hopefully, you now have a better understanding of the underlying networking aspect of the world wide web. TCP/IP is integral to things such as p2p, web-browsing, and email.
Resources
http://www.garykessler.net/library/tcpip.html
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/centri4/user/scf4ap1.htm
http://en.wikipedia.org/wiki/Internet_Protocol_Suite
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