The term Internet is a contraction of ‘interconnected networks’ and, indeed, the Internet is a gigantic global collection of linked networks. The networks that make up the Internet can range in size from tiny (just two or three connected computers) to massive (thousands of interlinked machines). An Internet service provider (ISP) is a telecommunications business that delivers Internet-related services such as access to the Internet, domain name registration, website hosting, etc. ISPs enable you to connect to the Internet. When you use your computer to access the Internet from your home, you most likely connect to an ISP via a modem, a local telephone number, or a dedicated high-speed line. When you connect to your ISP, you become part of their network, which allows you to access the Internet.
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The networks are connected using routers. A router is a specialized computer that directs traffic on the Internet. As the Internet consists of hundreds of thousands of smaller networks linked together, routers are necessary. For example, when you want to visit a particular website, you type the site’s address into 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 path through all the networks to reach this destination. This determination is based on the traffic in different parts of the Internet and the available connections.
The networks in a particular region may be grouped into a mid-level network. Or they may be linked 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 another part of 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. The Internet backbones are a collection of networks that link extremely powerful supercomputers. The backbones are made up of fiber optic trunk lines (aka OC for the optical carrier). The fastest OCs can transit 2.488 gigabits per second! There are many high-capacity backbones around the world, all interconnected at various NAPs. They enable everyone to communicate freely with everyone else on the planet, no matter where they are.
As you can see, the Internet is a veritable jumble of interconnected networks. These networks are linked using a variety of communication technologies that vary from very slow to ultra-fast. And, given the way that routers decide the most efficient route, your data may circumnavigate the world before reaching its destination. For example, a request from a surfer in Dublin to view a website hosted in London seldom travels directly from Dublin to London; it is likely to be sent via the Americas should this be the fastest route (as measured in milliseconds). The problem is that the further data has to travel, the more it deteriorates or fades. Repeaters are pieces of hardware that amplify or refresh the stream of data. Boosting the data signals enables the data to circumnavigate the globe yet arrive intact at its final destination.
Various types of equipment are used to connect the various lower-order networks that make up the vastness of the Internet. These include bridges, gateways, and hubs. Bridges connect LANs. They enable data from one local area network to pass through another LAN en route to yet another LAN. Gateways are similar to bridges. However, they also translate data from one type of LAN to another. For example, they can translate data from a UNIX system to intelligible on an Intel-based system. Finally, hubs link groups of networks so that the computers in any of the networks can talk to all the other computers in the other networks.
Servers and clients
All the computers on the Internet are either servers or clients. Servers are machines that provide services to other machines (hence the name). There are various kinds of servers, each with specific functions. For example, web servers host websites, while email servers send and receive emails. FTP servers (file transfer protocol servers) upload and download files. One server machine may contain software for several service functions. Clients are computers that are used to connect to servers. For instance, you can connect to any website from your home or office computer. The computer you use is known as a client. When your client machine connects to a server, it will connect with specific server software running on the server. So if you are sending an email, your client machine will be talking to the email software on the server.
To recap, the Internet is a single gigantic network of networks linked using a wide variety of technologies. The millions of individual networks, small and large, make up the Internet owned and operated by numerous individuals, small businesses, and large corporations. This means that the Internet is built on cooperation and that nobody actually owns the Internet.
This lack of ownership might suggest that the Internet is subject to disruptions. Not so. When an individual network has problems, it merely drops out of the overall network, but only the computers on that network are affected. The computers that were communicating through the broken network, using bridges or gateways, will have plenty of alternate channels for doing their business.
In addition, the Internet Society, which was founded in 1992 as a non-profit association, facilitates the open development of the standards, protocols, administration, and technical infrastructure of the Internet… ensuring the smooth evolution and operation of the network of networks.