At its very simplest, a network of computers is just two or more computers that have a way of sharing work, devices or information back and forth between them. That holds true whether you've connected two laptops in your basement, or 2,000 computers at a factory, or millions of them on the internet. One thing that all networks have in common, however large or small, is that they all have the same building blocks.
Individual Workstations – the End-User Component
The most fundamental of network components is the individual workstation. If you look around your office, these are the computers that make up your network, and they're the machines where the end users' actual work is done. Most of the time, these are full-fledged personal computers in their own right. They have all the main components of a computer – a large hard drive, plenty of RAM and so on – and they can work independently, away from the network, if they need to.
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Not All Workstations are Equal
That doesn't mean every workstation on the network has to be a full-blown computer. An ordinary laptop or desktop computer contains a lot of things that aren't necessarily needed for network use, because they're shared on the network. You don't need a powerful processor of your own if most of the processing takes place in a massive data center, for example, and you don't need a big hard drive if you have access to limitless storage in the cloud. Instead, many companies use bare-bones computers called thin clients, with just enough memory and processing power to boot up and get onto the network. In large companies, that can add up to a substantial saving.
Even mobile devices can be considered workstations. If you connect to the network with a phone or a tablet to sync appointments or schedules with your coworkers or to upload files and photos for use on other machines, your phone itself can be considered one of the network's workstations.
A Server (or Not)
Some networks revolve around a central server, or a group of servers. You can think of a server as the main computer in a network, acting as a sort of manager or "traffic cop" to make sure everything runs smoothly. Generally, they'll have more powerful processors and often more of them, and they also have the ability to communicate at high speed with large numbers of computers and other devices.
Servers vary pretty widely. In a small network of a few computers, it might be the same as any other machine except for added RAM and a larger hard drive. In a corporate setting, a single data center might contain thousands of servers mounted in racks in a specially cooled room, all acting as a single oversized computer.
In some networks, usually small and simple ones, you might not use a dedicated server at all. Instead, those networks run on a peer to peer basis: All of the computers are treated as equals by the network, and all of them handle some share of the network's operations. Peer to peer networks aren't the high performance option, but they're relatively easy to set up and administer.
The Backbone of the Network
The difference between a network and any old room full of computers is that the computers in a network can talk to each other. They can communicate in two main ways, either through some sort of physical connection or wirelessly. Older networks used a thick TV-style cable, but you'll seldom see that anymore. Most modern networks use a lighter wire that's flat and has a larger version of the connector used for landline telephones. You might also see fiber-optic network cables in some settings, which are even smaller, lighter and faster.
Networks without cabling communicate wirelessly, through radio waves. The most common type of wireless networking uses the 2.4 GHz or 5 GHz band of radio frequencies. There are several versions of the wireless networking specification, all part of the 802.11 standard established by the IEEE, the international body of electrical engineering. The two most recent at the time of publication were 802.11n and 802.11ac, usually shortened to "wireless n" and "wireless ac," which give better performance than the older 802.11a, b, or g.
A Connection to the Network
Your house needs a driveway to get your car onto the street, and your computer needs a way to get onto the network. You'll find that on your computer's spec sheet as its NIC, or network interface card. The term is a bit old-fashioned, because it dates from a time when networking was an optional extra: You'd have to install a network card into one of the computer's expansion slots. Now, most computers come with both wired and wireless networking built right in.
Shared Software to Work With
There's a software component to networking as well, because connecting all of those computers together is pointless if they don't have anything to do that makes use of their ability to communicate. That comes in two parts, the software that makes the hardware work properly and then the actual applications you need to use to get work done. The first kind is something most users never need to think about, because getting the network up and running is someone else's problem. If you're a network administrator, making those programs work smoothly is what you do and how you earn your paycheck.
The actual applications you use on the network can be anything from Word or Excel to your favorite role-playing game. That's mostly of use at work, where you might have several people working on a given project. Instead of sending memos back and forth, and laboriously printing out revised documents, you can each edit drafts on your own machines and send them back and forth with the changes and comments visible for everyone to see.
Shared Storage and Other Devices
Networks might also include any number of other miscellaneous devices, which help make up a fully functioning network in the same way the main components of a computer come together with your choice of accessories to make up a fully functional workstation. The difference is that these accessories, or peripheral devices, are shared. Where your own computer might have a hard drive, the network's machines might share an array of drives in a network-attached storage system. At home you might have a printer for your own sole use, while at work you might share two with a whole department.
Even the modem you use at home for wireless internet is a good example of a shared resource. Twenty years ago you might have put a modem into each computer and all accessed online services separately. On a modern home network, the modem has its own wireless router, and all of the devices in your home – from computers to cellphones to smart TVs – can share it effortlessly.