The types of computers

What should we sort computers by?

The list you see in a shop is not a classification, it is a shelving plan. Gaming, office, student. Those names do not tell you how one machine differs from another; they tell you who the seller wants to sell it to.

Two questions produce a real classification. First, how many people does the machine serve at the same time. Second, how many different jobs is it allowed to do. A laptop serves one person and can turn its hand to anything. A server serves whoever comes asking at that moment and usually does only a few defined jobs. The internet modem in your home does one job and will keep doing that same one job for the rest of its life.

Those two questions give you three main categories: personal, shared, and embedded. There is an older category too, the mainframe, the large institutional machines whose history the Computer History Museum keeps, and outside banks and large organisations few people work with one up close.

Personal computers: desktop, laptop, tablet, phone

Four shapes of one thing. All four were built for a single person, and what separates them is where they get used and how much you can meddle with them.

The desktop, the box by the desk, does not move and has mains power. That is why its parts can be larger and hotter, and why for the same money it usually comes out stronger than a laptop. A part that fails is replaced on its own.

A laptop is the same thing folded up with a battery added. You pay for that portability in two places: price, and repairability. In a great many current models the memory and the battery are attached to the mainboard, and swapping them is not a job for any technician.

Tablets and phones are one family: a touchscreen, an operating system with an app store, and a list of permitted jobs decided by the maker. They are excellent for consuming, meaning reading, watching and replying. For producing, meaning long writing and working in several windows at once, they still lag, and clipping a keyboard onto a tablet does not entirely fix that.

One simple rule holds across all four: the more the machine is carried, the more you pay and the less you can repair it.

What exactly is a server?

The server everybody has heard of is not a supercomputer. It is a computer with a different job: it does not switch off, and it answers whoever comes asking.

What separates it from your laptop is not power, it is three habits. First, it never turns off, so its parts are chosen for uninterrupted work rather than for a few minutes of peak. Second, it has no screen and no keyboard and is run remotely by typing commands. Third, several people use it at the same time, and a large part of its job is making sure none of them notices the others.

When you open a website, your browser is talking to one of these. The more precise name for the computer a site sits on is a web server, and the MDN documentation carries the exact definition. If you want to put up a site of your own, instead of buying a whole server you usually rent a slice of one; that slice is called hosting, and the differences between its kinds are unpacked in our hosting guide.

Why do you never see most computers?

Take a look around you. The modem, the card reader in a shop, the security camera, the programmable washing machine, the car, the lift. Inside each of them sits a small computer running one program, and it will never run anything else for the rest of its life. This category is called an embedded computer.

We are not going to give you a number for it, because we do not have a trustworthy one. The reasoning is simple though: an ordinary home has one or two devices people call computers, and several more that contain a chip and that nobody calls a computer. So most of the computers in your life are the ones without the name on them.

If you want to hold one of these and look at it, an Arduino board was built for exactly that: a small computer on a board that takes one program and repeats it. Arduino own documentation carries the plainest explanation, and for understanding this category it beats any textbook definition.

Why does the category matter? Because the same rules you know for a laptop apply to these, and nobody thinks about them. A modem whose default password was never changed is a computer connected to the internet, with a password published on the internet.

Which one do you need for the work you do?

An opinion, and then three places where the opinion does not hold.

For most people reading this the answer is a mid range laptop and nothing more. The reason is that in everyday work the bottleneck is almost never the processor; it is too little memory and a slow disk. The extra money spent on a more expensive processor is simply not visible in opening a browser, writing, and watching video.

Now the three places the opinion turns out wrong. If you edit video or work with 3D files, the hardware genuinely is the bottleneck and none of this applies to you. If your whole job happens in a browser and you are always on the move, you may not need a laptop at all. And if the machine is going to stay put on a desk, a desktop gives you more for the same money and can still be upgraded next year.

The next step is to look at what is inside these machines and which part actually sets the speed. The answer is usually not the part printed largest in the advertisement.