At the moment we have four variants of computer equipment: Desktop, Laptop, Tablet and Smart phone.
We will talk about Windows OS, which is used by about 90% of users of Desktops and Laptops, and about 70% of Tablet and Smart phone users use Android OS.
However, in my opinion, the theme OS Windows, is relevant only now. After 10-15 years, perhaps no one will use this OS. The fault is, first and foremost, the company Microsoft itself. This I hope to prove in this book. Here you can see "About Windows" if you click the button.

So, I'm sure that more than 90% of users can use any of these options without losing, for themselves, any functions.
By the way, this topic arose because I'm tired of explaining simple things to acquaintances, little-known and completely unfamiliar people. The fact is that all private individuals and all companies that sell computer equipment are not at all interested in helping you acquire exactly what you need. This happens for a very simple reason. Everyone needs to earn money, therefore, the more expensive the equipment they sell, the more profit they will get.
But, the more expensive the technique is, the better it is, any unsophisticated user will say. Theoretically, we can agree with this, but in practice the cost is determined by a very large number of factors and, first of all, by technical characteristics. And, if the technical characteristics are the same, the value increases on behalf of the company. The most expensive products are offered by Apple. Then Sony, Lenovo, HP and so on. However, if you need a technique for a type of work known to you, then, first of all, you need to determine the technical characteristics, and not the company name.
But, for starters, you just need to find out what you are buying a computer for, that is, what you need to do, what work to perform.
If you have a task that you are going to perform on your technique, then you should get acquainted with the description of the computer program with which you will work.
The minimum parameters of the equipment, and OS, in which the program works, as a rule, you will find in the description of the program itself.
So, consider the following options in more detail:
- Desktop
- Option first Game PC Desktop.
- Option the second is the average Desktop.
- Option three is the cheapest Desktop.
- Select Monitor for Desktop.
- Desktop or Laptop?
- The fourth version of Laptop.
- Laptop or Tablet?
- Option the fifth Tablet.
- Tablet or Smart phone?
- Option Sixth Smart phone.

Desktop.
Desktop or floor versions of the PC case are intended for stationary use and their main advantages are as follows: - Ensure continuous operation for a long time. In a literal sense, they can not turn off for years, perhaps, for preventive works. That is, it is quite possible to use it as a server, in a house or office or, say, place on it a website that will be available around the clock. Having an "open architecture", proposed by IBM, back in the 80's, motherboards have expansion slots. Which allows you to change the configuration, including additional devices and upgrade existing equipment. For example, if you need to work with more complex graphics, you can change not the entire computer, but only the video adapter. The same can be done with a sound card. And also, if some components fail, on the motherboard, open architecture, they can be replaced by additional cards inserted into the slots. - In the case you can place two or more CD / DVD and two or more HDD. - Change, if necessary, a more powerful, power supply. - Change the processor, put a more powerful radiator, or, in the end, without any problems, change the motherboard.
On PC Desktop with an open architecture, you usually install Windows OS or Linux / Unix OS.
By the way, Apple Desktop does not produce "open architecture". It releases Monoblocks "all in one case" therefore something to modernize, it is impossible .

To "cheat" customers, at a great cost manufacturers come up with a special Game PC. This is a case with a backlight (blinking LEDs), a motherboard, also with a backlight, even a memory with illumination. Naturally, this design will not work faster, but it will cost much more.
In addition, on the Game PC put instead of a regular disk (HDD) drive SSD HDD (Solid State Drive) this hard disk consists of a set of memory chips.
The speed of the Operating System (OS), on SSD HDD, will naturally be much higher.
To buy the finished Game PC, in the store, it is not worth it, for three reasons.
1. It will not install SSD HDD (with rare exception).
2. It will be installed OS Windows 10, because on all new computers, install a new OS.
3. Extra costs for the cost of unnecessary OS and additional costs, because you will have to install SSD HDD and, for example, OS Windows 7.
No one, self-respecting gamer (a person addicted to games), does not use OS Windows 8 or 10. Some gamers, as I read, use Windows 98, but installing it on modern hardware is not an easy task (due to lack of drivers). By the way, it is proved that OS Windows 10 and 8 should be installed only on SSD HDD, because they can not work quickly on ordinary HDD, and after a couple of months your system will become very slow.
Typically, the Game PC is assembled on its own or ordered a completely specific configuration, necessary for one or the other game. (Necessary parameters of the equipment, you will find in the description of any computer program).
But, the game programs are created not only for entertainment, but for selling new equipment, so very soon your favorite game can begin to require a new processor or a new video card.
However, if you do not get carried away with modern graphics, similar game programs can be found for less advanced technology. For example, 20 years ago Game PC was with a 486 MHz CPU, it's less than 0.5 GHz. And, for sure, there was a toy with similar functions, but, according to current concepts, with terrible graphics.

The second version is the secondary Desktop.
Virtually any application program will run on a PC with a CPU from 2 GHz to 4 GHz. Naturally, the higher the CPU speed, with enough memory, the faster your program will run.
The vast majority of unsophisticated users, mistakenly believes that the more memory, the faster their technology will work. This is not so, because the memory load is determined by the amount of information processed. (That is, if we talk about a long sequence of pictures: The small size of each picture, of course, will use less memory than the sequence of large pictures).
With 100% CPU usage, the memory can be used less than 50%. However, with a lack of memory, of course, the system will slow down.
You, at any time, can open Task Manager and see the load of memory and CPU.
On such PC it is quite possible to do cartoons (less CPU speed, longer, in time). You can work in AutoCAD, in CorelDraw, Photoshop in other graphics programs, work with video, sound and other files.
The only thing that you need to pay attention to: - When working with graphics programs, it is necessary to take into account the capabilities of the Video card, which can be replaced, if necessary (more details - "Choosing a monitor").

The third option is a cheap Desktop.
If you are not going to work with serious graphics and sound programs, then it is quite possible to get by with a PC from 1 GHz to 2 GHz. You will not have problems with the Internet, with Video and sound files. You can, without problems, create any documents, for example, in Microsoft Office. Play simple toys, etc.
Host such a configuration of the computer in the usual (medium-sized) case - Desktop.

Choosing a Monitor.
Very bad, at the moment, are the old monitors, which had a screen resolution of less than 1200x720 pixels. But this and a smaller resolution is found on Laptops, Tablet-ah and Smart phone.
The screen resolution is the number of pixels horizontally and vertically with which, on the screen, an image is formed (Pixel, these are the three colored dots Red, Blue and Green).
The smaller resolution of the screen is bad that today's websites basically have a size, in width, up to 1200 pixels and if you do not have such a screen resolution, the page of the site will not fit, on the screen entirely and it will have to be shifted not only along the length ), but also in width.
Normal (average) is the screen resolution of the monitor, not less than 1600x900 pixels. With such a monitor, you can comfortably watch movies or play video games.
This resolution can be played back by the usual (at the moment) Video card built into the motherboard or placed with the processor in one chip.
But, for game programs, the speed of the normal Video card is not high enough, therefore, apply special ones.
A larger screen resolution, for example, 1920x1200, can show some 24 "monitors.This monitor you can turn and comfortably browse the Internet.Sites are usually narrow and long, therefore, for viewing them, the monitor turned to the side is best suited.
Monitors with a large screen size can show, for example, 2500x1600 pixels. There are monitors with a higher resolution, for example 4K and 5K.
4K (full-frame) has a resolution of 4096x3074. With the UHD index the resolution is slightly less than 3840x2160, such monitors are quite affordable, for the price. Use of these monitors, it is desirable when working with large graphics files. For example, when creating drawings in AutoCAD. For working in Photoshop or other graphics programs. This screen resolution can create a special, but not very expensive video card. (If we do not talk about gaming software).

An example of a monitor with a resolution of 3840x2160. Here are opened in Google EBay and Photoshop .Full-size 4K monitors and 5K with a resolution of 5120 x 3840, at the moment, very expensive.

Desktop or Laptop?
Desktop is a PC that you can turn on and off for at least a year. Neither a laptop with such a task can not cope, because it will quickly fail.
The fact is that in a small case, to cool the components, it is not possible to place a large heatsink and a large fan. To increase the area of the fan cooled surface, a radiator with a large number of metal plates is used, leaving a very narrow passage between them for air.
Until the passage between the plates is clean, the cooling is normal. But the working fan sucks in the air, and with it the dust. Dust clogs the narrow aisles between the plates and the cooling deteriorates, and then it can completely stop. As a result, if the CPU is overheated, the CPU will shut down and turn off the PC, because it has this function. And other cooled components do not have such a function, for example, a video chip can burn out or, at best, just be discarded. It will be required, as a minimum, to repair the motherboard, or replace it.
That is, the main problem in the design of Laptop, it's dust. If you do not use your Laptop for a long time and use it every day, then you need to clean it from dust, you probably need it once a year. And if you work on it for 8 hours, every day, then you'll have to clean it every month.
Some companies, such as HP and Dell, are very fond of making complex case designs. To clean the radiator, you will have to completely disassemble the Laptop, remove the motherboard and only after that, you can remove the fan and get to the radiator. Very seldom there are old designs in which it was possible to remove a small back cover and at once to reach to a radiator or the fan.
In modern constructions it is very rare!

The fourth version is Laptop.
How to choose a Laptop: Some manufacturers try to convince users that toy technology can also be a full-fledged working tool. To do this, in a small case you need to put a good CPU, a good Video card and a screen with a decent resolution. The cost of such a toy, naturally, increases several times. But, even if you apply several radiators and a few fans, as you already know, they can get stuck with dust and your expensive toy turn into a piece of plastic and metal.
A good modern Laptop has a CPU of no more than 2.2 GHz. More common are cheaper and slower. And, very rarely, with CPUs over 3 GHz it's them that are trying to sell as a Game PC. And the cost of such a laptop, can be compared with the Desktop Game PC.
The most correct option, when choosing Laptop, is not to try to look for improved parameters with a good video and sound card. And to search with the processor, in which the video card is built. In this case, as you understand, the processor will turn off when the processor overheats, and there will be no problems with the video card placed separately.
The next question is very important. It is necessary to look for a housing design in which the bottom cover has holes (usually a grid) into which the fan sucks in air. Through these holes you can see the fan blades. And on the side of the case, you can see the radiator plates. If you find such a design, then you will not need to regularly seek help from specialists, you can clean your Laptop. For cleaning, from dust, only once a week, you need to blow the air into the radiator and use a vacuum cleaner to remove the dust, through the hole in which the fan sucks in air. Naturally the Laptop should be turned off.
The next problem. Dust falls not only in the radiator, but also in the loops that fasten the screen, to the body. After a while, the loops stop working well. Opening a laptop becomes harder. This leads to the fact that the hinge is broken, but more often, the case itself.
This happens particularly quickly in miniature (thin) structures, because the materials for making such structures are also thinner and tiny. Already only on this occasion, thin Laptop to buy it is not necessary. Not to mention other problems, thin designs, such as poor cooling, because of which a quick failure of individual components or the entire motherboard is possible
Select the screen size. The most common screen size is about 15 "(inches) with a screen resolution not much larger than 1200 x 720 (the smallest convenient size, as already mentioned) .This is what Laptop should be chosen for. Do not look for larger or smaller size. it's not convenient if you need to wear it.If you need a large screen, you can get it by connecting your Laptop to the monitor or to the TV.
A smaller screen size will have the worst screen resolution. And if the screen resolution on a small screen is comparable to 15 ", then the cost of such a laptop will increase significantly. In addition, small, in size Laptops, as a rule, have weak processors and work, naturally, slower.
Do not buy a laptop with a narrow screen. Narrow screen, convenient only for watching movies and completely inconvenient for the Internet.
Do not buy a Laptop with a shiny screen, you need to choose matte. In this case, you can better consider what is on the screen, not your own reflection and no glare from any extraneous light sources.
Previously, all Laptop screens were matte screens, until some manufacturer came up with the silly idea to make them shiny. But, now, for example, Lenovo, calls its Laptops a professional technique, using just matte screens.
By the way, not only monitors, now there are even shiny keyboards. To work on such a keyboard is very difficult, if you need to see the letters written on it. However, such completely brilliant laptops are also sold - buyers, which is quite obvious, children, who are given a choice of models and people who buy the computer for the first time. Although it is these categories of users most of all need to see the letters on this keyboard. If you do not need additional problems, when using your Laptop, then choose matte, internal surfaces of the case, screen and keyboard.
With a processor of about 2 GHz, as you already know, on your Laptop you can perform almost any task. But, people who work a lot on the keyboard (not only writers, but also those who have to write many letters) prefer to use a regular keyboard. It can be fully connected using a USB port.
It is possible to process photos, but for this, it is better to use the usual "Mouse". It can also be connected using a USB port.
And, better, use a monitor, with a better resolution that you can connect, if you have a port, for a monitor.
If you are thinking of connecting a good monitor, keyboard and mouse to Laptop, then you should not buy it at all, choose Desktop.

Option of the fifth Tablet.
Choosing a Tablet, this is not a very simple question, because manufacturers offer a very large range of products. The cheapest will have a processor below 1 GHz and a poor screen resolution. Such Tablet can be used if you are satisfied with the picture that you get on the screen and you do not need to communicate in Skype (it slows down at low CPU speed).
You will not have problems with viewing your email and even, for viewing most movies. However, a poor screen resolution will make it difficult to work on the Internet. The fact is that the pages of sites on the screens of mobile devices are compressed, therefore, in poor resolution, theoretically, it is easier to work than on a monitor screen, or Laptop, which has bad resolution. But, in practice, it is desirable to choose a screen option, with a resolution of at least 1200 pixels on the long side.
If you want to use Tablet instead of Laptop, first of all you need to choose the screen resolution you need. Quite sufficient, there may be a resolution, for example, 1200 x 720. However, you can find and much better. As an example: Samsung Galaxy Note 10.1 (SM-P601) has a resolution of 2560x1600, such parameters do not have any of the screens on Laptop-ah.
Then, you need to select the processor speed. In order not to spend extra money, it is possible to stop on the middle version, it is about 1, 5 GHz.
If you need a lot of typing on the keyboard, then using a touchscreen is not convenient, so you should look for an option that allows you to use a remote keyboard. Usually, such a keyboard is placed in the case for this particular Tablet model.
If you need to save, or transfer the information (documents, photos) that you created on your Tablet then you can send them by e-mail, or that it seems to me somewhat better (more efficiently) to use a flash disk. That is, you need to choose a variant of Tablet, in which there is a socket for the flash drive.
For viewing, on the big screen of the TV, at your Tablet, (and also at Smart phone), there can be some variants. For example, the HDML port, if available, you will get not only a picture, but also a sound, on the TV, if such a port is also on your TV.
You can connect to the TV and using Wi-fi, if such a function is on your TV.

Tablet or Smart phone?
If you have a Tablet, then it does not make sense to buy a Smart phone, and twice paying for using the Internet, you can buy an ordinary mobile phone without access to the Internet.
Most models - Smart phone have a slower processor, a smaller screen size and a worse resolution, But it's quite possible to replace, using the Smart phone, not only the Tablet, but also the Laptop.