What is Operating System?

The operating system is the one program running at all times on the computer, with all else being system programs and application  programs. It manages the computer hardware and provides a basis for aplication programs and acts as an intermeiary betweem the computer user and the hardware.



And write sevral your familiar operating systems in details.

1.DOS

DOS is a platform-independent acronym for Disk Operating System, which was initially introduced by IBM for the System/360 mainframe and later became common shorthand for the popular family of disk-based operating systems for x86-based IBM PC compatibles. DOS primarily consists of Microsoft's MS-DOS and a rebranded IBM version under the name PC DOS, both of which were introduced in 1981. Later compatible systems from other manufacturers are DR DOS, ROM-DOS, PTS-DOS, Embedded DOS (by General Software), FreeDOS , and RxDOS. MS-DOS dominated the IBM PC compatible market between 1981 and 1995. The operating system offers an application programming interface that allows development of character-based applications, but not for accessing most of the hardware, such as graphics cards, printers, or mice. This required programmers to access the hardware directly, usually resulting in each application having its own set of device drivers for each hardware peripheral. Hardware manufacturers would release specifications to ensure device drivers for popular applications were available.

2. Linux

A Linux-based system is a modular Unix-like operating system, deriving much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, access to the peripherals, and file systems. Device drivers are either integrated directly with the kernel, or added as modules that are loaded while the system is running.



The GNU userland is a key part of most systems based on the Linux kernel, with Android being the notable exception. The Project's implementation of the C library functions as a wrapper for the system calls of the Linux kernel necessary to the kernel-userspace interface, the toolchain is a broad collection of programming tools vital to Linux development (including the compilers used to build the Linux kernel itself), and the coreutils implement many basic Unix tools. The project also develops a popular CLI shell. The graphical user interface (or GUI) used by most Linux systems is built on top of an implementation of the X Window System. More recently, the Linux community seeks to advance to Wayland as the new display server protocol in place of X11. Many other open-source software projects contribute to Linux systems.

3.Ubuntu

Ubuntu is a free and open-source Linux distribution based on Debian. Ubuntu is officially released in three editions: Desktop,[10] Server, and Core (for internet of things devices and robots). All the editions can run on the computer alone, or in a virtual machine. Ubuntu is a popular operating system for cloud computing, with support for OpenStack.



A default installation of Ubuntu contains a wide range of software that includes LibreOffice, Firefox, Thunderbird, Transmission, and several lightweight games such as Sudoku and chess. Many additional software packages are accessible from the built in Ubuntu Software (previously Ubuntu Software Center) as well as any other APT-based package management tools. Many additional software packages that are no longer installed by default, such as Evolution, GIMP, Pidgin, and Synaptic, are still accessible in the repositories still installable by the main tool or by any other APT-based package management tool. Cross-distribution snap packages and flatpaks are also available, that both allow installing software, such as some of Microsoft's software, in most of the major Linux operating systems (such as any currently supported Ubuntu version and in Fedora). The default file manager is GNOME Files, formerly called Nautilus.



Ubuntu operates under the GNU General Public License (GPL) and all of the application software installed by default is free software. In addition, Ubuntu installs some hardware drivers that are available only in binary format, but such packages are clearly marked in the restricted component.

4.IpadOS

IpadOS is a brand new operating system released by the APPLE company, IPAD pro users now can run the beta version of IpadOS on their devices.

iPadOS features a multitasking system developed with more capabilities compared to iOS, with features like Slide Over and Split View that make it possible to use multiple different applications simultaneously. Double-clicking the Home Button or swiping up from the bottom of the screen and pausing will display all currently active spaces. Each space can feature a single app, or a Split View featuring two apps. The user can also swipe left or right on the Home Indicator to go between spaces at any time, or swipe left/right with four fingers.



While using an app, swiping up slightly from the bottom edge of the screen will summon the Dock, where apps stored within can be dragged to different areas of the current space to be opened in either Split View or Slide Over. Dragging an app to the left or right edge of the screen will create a Split View, which will allow both apps to be used side-by-side. The size of the two apps in Split View can be adjusted by dragging a pill shaped icon in the center of the vertical divider and dragging the divider all the way to one side of the screen closes the respective app. If the user drags an app from the dock over the current app, it will create a floating window called Slide Over which can be dragged to either the left or right side of the screen. A Slide Over window can be hidden by swiping it off the right side of the screen, and swiping left from the right edge of the screen will restore it. Slide Over apps can also be cycled between by swiping left or right on the Home Indicator in the Slide Over window and pulling up on it will open an app switcher for Slide Over windows. A pill shaped icon at the top of apps in Split View or Slide Over allows them to be switched in an out of Split View and Slide Over.



5.Symbian

Symbian, an almost dead operationg system once used by NOKIA.

Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. Symbian was originally developed as a closed-source OS for PDAs in 1998 by the Symbian Ltd. consortium. Symbian OS was a descendant of Psion's EPOC, and ran exclusively on ARM processors, although an unreleased x86 port existed. Symbian was used by many major mobile phone brands, like Samsung, Motorola, Sony Ericsson, and above all by Nokia. It was also prevalent in Japan by brands including Fujitsu, Sharp and Mitsubishi. As a pioneer that established the smartphone industry, it was the most popular smartphone OS on a worldwide average until the end of 2010—at a time when smartphones were in limited use—when it was overtaken by Apple iPhone and Android. It was notably not as popular in North America.