The term Internet is a contraction of “interconnected networks” and, in fact, the Internet is a gigantic global collection of linked networks. The networks that make up the Internet can vary in size, from tiny (only two or three computers connected) to massive (thousands of machines interconnected).
An Internet Service Provider (ISP) is a telecommunications company that provides Internet-related services, such as Internet access, domain name registration, website hosting, etc. ISPs allow you to connect to the Internet.
When you use your computer to access the Internet from home, you will most likely connect to an ISP through a modem and a local phone number or through a high-speed dedicated line. When you connect to your ISP you become part of their network, allowing you to access the Internet.
It is likely that the computers in the office where you work are connected in a network known as a local area network (LAN). This allows the computers in your office to communicate with each other. The LAN is most likely connected to an ISP and this connection allows you to access the Internet from your office computer.
Either way, your home PC or your office LAN becomes part of the ISP’s network. The ISP will then connect to a larger network to become part of that network. That network will connect to larger networks to create a worldwide communications system.
Thus, the Internet is nothing more than a network of networks. These networks connect computers using a wide variety of technologies, including conventional and high-speed telephone lines, fiber-optic cables, microwave links, wireless technologies, and satellite communications.
Networks are connected by routers. A router is a specialized computer that directs traffic on the Internet. Since the Internet consists of hundreds of thousands of smaller networks connected to each other, the use of routers is absolutely necessary.
When you want to visit a particular website, type the address of the site in your web browser. The address goes to the nearest router and the router decides where that site is on the Internet.
The router also determines the most efficient route through all the networks to reach this destination. This determination is based on traffic on different parts of the Internet and available connections.
Networks in a given region can be grouped into a mid-level network. Or they may be connected in a wide area network (WAN). A WAN covers a larger geographical area than a mid-level network. If the website you are looking for is within the same regional network or WAN, the router will send it directly to its destination.
However, if the website you are looking for is located elsewhere on the Internet, the router will send your request to a network access point (NAP). NAPs connect high-level networks, i.e., they allow access to Internet backbones.
Internet backbones are a set of networks that link extremely powerful supercomputers. Backbone networks consist of fiber optic backbones (also known as OCs or optical carriers). The fastest OCs can carry 2,488 gigabits per second!
There are many high capacity backbones around the world, all interconnected at various NAPs. They allow everyone, no matter where they are, to communicate freely with everyone else on the planet.
As you can see, the Internet is a real hotchpotch of interconnected networks. These networks are connected using a variety of communication technologies ranging from very slow to ultra-fast. And, given the way routers decide the most efficient route, their data can circumnavigate the world before it reaches its destination.
For example, a request from a Dublin internet user to view a website hosted in London rarely travels directly from Dublin to London; it is likely to be sent across the Americas if this is the fastest route (measured in milliseconds).
The problem is that the more data they have to travel, the more they deteriorate or fade away. Repeaters are pieces of hardware that amplify or refresh the data stream. Increased data signals allow data to circumnavigate the globe and arrive intact at their final destination.
Various types of equipment are used to connect the different low order networks that make up the immensity of the Internet. These include bridges, gateways, and distribution centers.