What is an operating system?

Many people use elec­tron­ic devices such as PCs, laptops, smart­phones, or tablets on a daily basis. And all of these devices are usually running an operating system (OS). But only few users know what this software can do and why it comes pre-installed on most devices. While laptops and desktop devices usually run on Windows, macOS, or Linux, most mobile devices either run iOS or Android. And although most operating system differ widely; their core functions and structure are very similar in principle.

After you switch on your laptop, one of the first things to usually happen is that the system will boot up. Depending on the operating system installed, Windows, Linux, or macOS will launch. Only once the system used to run the device has been booted, users can launch their favorite programs, connect to the internet, or access their data. The operating system is not, however, re­spon­si­ble for the actual boot-up process. That’s what the BIOS is for.

But the BIOS only has basic func­tion­al­i­ties relating to the boot-up process. One of its tasks is to load the operating system which then takes over the whole system ad­min­is­tra­tion. Much of this happens in the back­ground. Windows and co. are also available as in­ter­sec­tions between the user and the computer. The OS allows users to make system setting changes to their devices, install programs, and uninstall ap­pli­ca­tions they no longer use.

Nowadays, most operating systems rely on graphical in­ter­faces and are designed to be user-friendly. Using just a few mouse clicks, the most important functions are easily ac­ces­si­ble for users. Menu nav­i­ga­tion tends to be intuitive. However, this was not always the case. Right at the start, when computers were used for sci­en­tif­ic and military purposes, operating systems were not yet in use. All tasks were solved by the machine itself without a network layer. But with the launch of the first PCs that were not the size of a wardrobe, operating systems became part of the standard con­fig­u­ra­tion.

The very first operating systems did not have a graphical user interface. Instead, they used the command line, which is still available as Windows Pow­er­Shell, for example. For each action, whether the opening of a data file, the nav­i­ga­tion of a file system, or the launch of a program, users had to know the correct command and enter it manually. Only once computers entered our home did simpler user in­ter­faces became the norm, with Microsoft (Windows) and Apple (macOS) now leading the market.

The operating system is at the core of the computer. Without this complex piece of software other ap­pli­ca­tions wouldn’t be able to run. The tasks an OS has to ac­com­plish are manifold and while some functions run primarily in the back­ground, many will run si­mul­ta­ne­ous­ly (fore­ground and back­ground ap­pli­ca­tions at the same time).

One of the most important functions of the operating system usually happens in the back­ground. The system ad­min­is­ters the entire hardware – inputs and outputs. The system uses a driver provided by the hardware producer to do so. This driver ensures that commands from devices and the hardware itself can be received and passed on. This allows for keyboard, mouse, screen, hard disk, graphics card, and all other com­po­nents that are part of a computer to function.

When you download software online, you will usually be presented with a choice of different operating systems. This shows just how strongly the pro­gram­ming of ap­pli­ca­tions is tied to the spec­i­fi­ca­tions of the operating systems. Basic computer systems have in­ter­faces which regulate the com­mu­ni­ca­tion with in­di­vid­ual ap­pli­ca­tions. This enables ap­pli­ca­tions to be assigned system storage, make use of pro­cess­ing resources, and be re­spon­sive toward commands entered by mouse and keyboard devices.

When a document is being written, it can be printed or saved as a file in a folder. The command, for example, to print a file, is trans­mit­ted to the operating system which transfers it to the printer. Working as part of a directory structure is only possible because of the OS. This type of structure does not exist on the hard drive itself.

In some cases, for example, in the case of business use, multiple people use a single device. But not all of them will be allowed to make changes to the system settings. Modern operating systems can be used to create different users and adapt their in­di­vid­ual rights. Every account can be secured using a password.

Even people without broad IT know-how should be able to use computers without dif­fi­cul­ty. That’s why operating systems must be designed with simple functions and options. Layper­sons should be able to use the most important parts of an OS ef­fort­less­ly. Ad­di­tion­al­ly, many operating systems – es­pe­cial­ly in the case of PCs – provide added options for pro­fes­sion­al users.

Because the operating system organizes the hardware, it’s also used to establish a con­nec­tion to the internet and other network com­po­nents. In this way, one can configure the computer to act like a network par­tic­i­pant, for example, by defining a specific IP address. A user can also enter the spec­i­fi­ca­tions for LANs and subnets to connect to another PC. Network settings allow users to make ad­just­ments to their DNS server.

Security is not tra­di­tion­al­ly part of an operating system’s core functions and can usually be adjusted using ad­di­tion­al software. Because computers are subject to constant threats online, many operating systems now come pre-installed with certain security measures. For example, Windows generally ships with a firewall and an anti-virus scanner.

Operating systems can be cat­e­go­rized under various aspects. One can dif­fer­en­ti­ate between operating systems for mobile devices and those of desktop PCs or laptops. Or one can look at the un­der­ly­ing software by dis­tin­guish­ing Unix-based systems (for example, macOS and Linux) from VMS-based OS such as newer Windows versions. Older editions of Windows expand on DOS. There are also operating systems that are specif­i­cal­ly con­fig­ured for servers. Generally, the best-known and most widely dis­trib­uted operating systems are Windows, macOS, the various Linux dis­tri­b­u­tions, iOS, and Android.

Windows is probably the best-known operating system worldwide, and with over 30 years on the market, also one of the oldest. It’s likely that most people will have used a Windows PC at some point in their lives. That’s partially because Microsoft tends to pre-install the OS on many of its products and computers. A new version of the operating system is released regularly. Windows 10 is the latest edition, but how these versions are counted tends to change. That’s why the current version may not actually be the 10^th version of the OS.

At around the same time when Microsoft launched its first OS, IT company Apple issued its first operating system. Back then, the Macintosh OS simply referred to as “System” was well-known for its graphical interface. Later called Mac OS X, it is now commonly referred to as macOS to match the company’s mobile operating system iOS. One of the special features of macOS is that the operating system only runs on Apple hardware.

Linux is one of the best-known al­ter­na­tives to Microsoft and Apple OS. Even if you’ve never used it before, most computer users will have heard of Linux. It has an un­jus­ti­fied rep­u­ta­tion as a more com­pli­cat­ed coun­ter­part to Windows. In reality, Linux is just a kernel which is installed across various dis­tri­b­u­tions. Among the best-known are Ubuntu, Debian, openSUSE, Fedora, or CentOS.

The Apple iPhone is one of the most suc­cess­ful smart­phones available on the market and has led to the wide­spread use of the iOS operating system. The OS which comes pre-installed on every Apple smart­phone, follows the same approach as macOS: users should be able to navigate the various menus and programs ef­fort­less­ly. What one gains in terms of user-friend­li­ness, one loses in freedom. Apple iOS is known for re­strict­ing ad­just­ment to its system settings.

One of the other major players on the mobile OS market is Android. The system was created by Google and takes a very different approach to its main com­peti­tor Apple. Android is available as a free software and provides a variety of options for setting ad­just­ments. Android is not dependent on a single device man­u­fac­tur­er. Almost every smart­phone, apart from Apple devices, now comes pre-installed with Android.