Today’s technologies have a lot in common, believe it or not. Whether you use your smartphone for most of your interaction with the Internet, or spend your day working on a laptop or a fancy desktop computer with lots of storage space and a powerful graphics card, these technologies have very similar structures.

These devices allow us to perform a large number of tasks, including creating documents, accessing services on the Internet, and even playing games. Learning to use these devices can be daunting because of the large number of things they allow us to do, and it’s difficult to know where to begin.

However, the device is only useful if we can do the tasks we need to do. We generally purchase devices to do a set of tasks we are interested in. The tasks are accomplished through specific apps (applications or programs). In order to start apps, we interact with the operating system through the desktop interface or home-screens, depending on the device. Every computer, tablet and smartphone comes with an operating system (OS). The common operating systems include Windows 10, macOS, iOS and Android. 

A very nice feature is that once you become familiar and comfortable with one device it can make it easier to move to other devices because the principles are similar. We can look at the operation of modern technologies as a layer cake as shown in Fig. 1, with us “Users” at the top and the device hardware at the bottom as in the figures below. The left-hand cake is for phones and tablets, while the right-hand cake is for computers.

Technology layers from hardware to users.
Fig. 1: Device (left) and Computer (right) Layers

The Layers:

  • Users
    • At the top of our diagrams in Fig. 1 are the people who are trying to do important and interesting things. We turn on our devices and once we’ve logged in, we open the apps we need to: check our mail, browse the Internet, book flights and hotels, and get updates on all our family and friends on social media.
  • Applications (Apps) 
    • The software that we run on our devices have a number of names, including programs, executables and applications or apps. Apps have fairly limited functionality in that they are designed for a small number of focus tasks. If you want to write a letter you need a word processor such as WordPad or Microsoft Word on Windows, or Pages on Apple products. To create a spreadsheet, you could use Microsoft Excel on Windows, or Numbers on Apple products. A word processor won’t be able to play a movie, and a music playing app won’t be able to create a spreadsheet. The power of our devices comes in having apps to do the tasks we need to do. 
  • Operating System (OS)
    • The Operating System (OS) itself is also software. The OS is a program that starts when we turn the device on. This program interacts with and controls all the hardware on the device. The OS controls which app is running at any instant, decides which to run next and ensures that no single app gets to run and exclude others. The operating system acts as an interface between programs and the hardware. For example, if we are editing a document in a word processing app, and we want to print the document, we execute the Print command. The word processor sends the document to the operating system and the OS sends the document to the printer. It’s only the operating system that understands how to communicate directly with the printer. This is true of other functions in our devices as well.
  • Hardware
    • The hardware is any part of the device that we can touch. The hardware includes a motherboard, processor, memory, storage, cameras and a variety of other components that allow the device to function. These are the parts that are tangible. Phones, tablets and Apple computers don’t have much flexibility for changing components, but Windows computers are often designed so that we can add or replace components to get new or better functionality.

When we start our devices, the operating system starts first. This program is essential for the operation of the device and controls all the hardware in the device. When we start an app, it will run in the environment of the operating system and many operations that an app needs to have done occur by interacting with the OS. It is important to note that you can have an operating system without apps running but you can not have or start apps without an operating system. If your operating system isn’t running your device isn’t turned on!

Fortunately, as you become familiar with one of these devices you will develop reasonable expectations of behavior for other types of devices. What you learn about your smartphone can often be transferred to your computer – not the details of which button to press, but the general principles of how the devices work.