This page is dedicated to an explanation of how the Internet or the "Web" works. First, consider these conceptual drawings:
The home PC is connected to the Internet through a telephone line to a server computer at the Internet Service Provider (ISP). All of the ISP servers are connected together through special data communications lines around the world. This drawing depicts the connectivity of the physical equipment. As you can see, it looks like a "WEB", hence it's name.
The ISP has assigned to it many Transmission Control Protocol (TCP) / Internet Protocol (IP) numbers (205.206.113.xxx). TCP/IP is the network protocol that all computers on the Internet (which is a network) use to communicate with each other. Each IP is an electronic identification number. IP version 4 (IPv4) sets available addresses in 4 octets separated by dots. The ISP server can assign many different IP's. To illustrate this, there is a .xxx at the end of the server IP's in the drawing. This is the last octet in the IP. Each octet can range from 1 to 255 it cannot be 256 or greater. 205.206.113.1 is an electronic identification that is unique and different from 205.206.113.2 and so on. Each IP number is a different unique electronic identification. So the server has a unique IP number as well as all other computers connected to it. The ISP server computer assigns unique IP numbers to every computer that connects to it. This server and other specialized equipment routes all data to the right lines via the IP number. In fact, all data on the Internet is routed to the correct place via the IP number. The equipment that routes IP numbers is called a 'Router'. Each node of the Internet in the picture represents a Router.
IP Assignment:
IPs are assigned to the ISPs by www.arin.net . This ensures that no two computers get the same IP. At the ISP, the network administrator assigns the IPs to all of the devices, routers, servers and dial-up chasses. To assign the end user with an IP, the administrator can either manually give you a static IP or a dynamic IP. A static IP is one that never changes while a dynamic IP changes every time you connect. Since there are a limited number of V4 IPs, the end user typically gets a dynamic IP. Static IPs are typically available for an extra charge.
Dynamic Host Control Protocol (DHCP):
ISP servers and dial-up chassis use a server program called DHCP to automatically assign end users with a dynamic IP. When you connect to the Internet through a dial-up modem, your modem calls a modem at the ISP. After the two modems negotiate a connection speed, your computer sends your username and password to the ISP to authenticate you as a registered user of that ISP's services. Once you are authenticated, the ISP server or dial-up chassis sends you your IP address through DHCP and the ISP's Domain Name System (DNS) IPs.
Domain Name System (DNS):
The DNS is an alphabetic to number translation table for IP electronic identifications. This is used to make it easier for human beings to find ISP's on the WEB. For instance, would you rather type in www.website.com to go to a website or would you rather have to type in 207.112.255.131? Obviously, words are easier to remember. The words www.lasercannon.com are also referred to as a Uniform Resource Locator (URL). The last two words separated by a dot are known as the Fully Qualified Domain Name (FQDN). FQDN's are unique and available for a fee to everyone by an Internet registration service such as www.networksolutions.com.
Protocols.
The word protocol is synonymous with language or syntax. By using standardized, universally agreed upon languages, all of the computers on the Internet can communicate and exchange data with each other. Browsing the web as you are doing right now by reading this page uses the Hyper Text Transfer Protocol (HTTP). That is why it is syntactically correct to refer to a URL as http://www.lasercannon.com instead of just www.lasercannon.com. TCP/IP is a protocol that defines the the way data is transferred between computers on the Internet. TCP/IP is used as a transport mechanism to send other protocols such as HTTP, Electronic-Mail (POP3/SMTP), File Transfer Protocol (FTP), and News (NNTP).
Wrapping up:
Although data is physically transmitted over the phone and Internet lines to physical computers around the globe, all computers on the WEB can talk to each other. The wires that connect the computers and the assignment of unique electronic ID's makes the physical locations of the equipment irrelevant. Let's use E-Mail as an example. To access your mail, your computer sends your password information to the mail server. How does your computer know where to send it? Because the server has an IP and DNS. When your mail program was set up on your computer, you had to tell it the name of the mail server, like mail.website.com. The password information is nothing more than data. So the combination of the mail server IP and the password data is what allows you to access your mail. For more detailed TCP/IP information, look at this page.
Caveats:
It is possible to screen IP numbers. Since the server knows the IP of the data originator or requestor, that IP number can be used by the server to block the information flow. The server can also log and track the IP numbers flowing through it or requesting data from it. In effect, one could prevent mail requests that originated with IP numbers outside of the IP number range assigned by that ISP. This technique can also be applied to FTP, News, and HTTP. So it is possible to block certain IP's from accessing email, reading web pages, and downloading files. This is generally done to limit access to information on the WEB.
