Pariksha SaathiLesson 4 of 10 · Computer Knowledge
Software and Operating Systems: Types, Functions, Booting and Files
Drafted with AI assistance and fact-checked on 28 October 2026; not yet read line by line by a human editor. Spotted a mistake? Tell us. Editorial standards & corrections
Software and its kinds
Hardware is the physical part of a computer; software is the set of programs that tells the hardware what to do. System software runs and manages the computer itself: the operating system, device drivers (which let the operating system talk to a printer or graphics card), language translators and utility programs. Application software helps the user do a particular task: word processors, spreadsheets, web browsers, media players, accounting packages and games. It may be general-purpose, sold to everyone, or custom-made for one organisation. Firmware is software stored permanently in ROM or flash chips on the hardware, such as the BIOS or UEFI of a computer, and sits between hardware and software.
Utilities and licences
Utility software maintains and protects the computer: antivirus, disk cleanup, the disk defragmenter (which gathers the scattered pieces of files on a hard disk), backup tools, file compression (ZIP) and disk formatting. By licence, proprietary or closed-source software keeps its source code secret and is used on the owner's terms (Microsoft Windows, MS Office, macOS). Open-source software publishes its source code so anyone can study, change and share it (Linux, LibreOffice, Firefox, Apache). Freeware is free to use but usually closed, and shareware is given on trial and must be paid for later. Richard Stallman started the GNU Project in 1983 and the Free Software Foundation in 1985.
The operating system
An operating system (OS) is the interface between the user and the hardware and the manager of all resources. Its functions are process management (deciding which program gets the CPU and for how long), memory management (allotting RAM and taking it back), file management (creating, naming, storing and protecting files), device management (controlling input-output devices through drivers), security (user accounts and passwords) and providing a user interface. The core of the OS that stays in memory is the kernel; the shell carries the user's commands to the kernel. The interface may be a CLI (command line interface), where commands are typed as in MS-DOS, or a GUI (graphical user interface) with windows, icons, menus and a pointer.
Types of operating system
A batch OS collects similar jobs into batches and runs them one after another without user interaction, as on early mainframes. A multiprogramming OS keeps several programs in memory so the CPU is never idle. A time-sharing or multitasking OS gives each user or task a short time slice of the CPU in turn, so many users seem to work at once; UNIX is the classic example. A real-time OS (RTOS) must respond within a fixed time and is used in missile guidance, air traffic control, industrial robots and medical equipment. A multi-user OS (UNIX, Linux) lets many users share one computer's resources, while a single-user OS such as MS-DOS serves one. A distributed OS runs a group of networked computers as one system.
Windows, Linux and Android
Microsoft, founded by Bill Gates and Paul Allen in 1975, released MS-DOS, a command-line system, in 1981 and Windows 1.0, a graphical shell, in 1985; Windows 95 introduced the Start button and the taskbar. The Windows desktop has the taskbar, Start menu, icons, File Explorer, Control Panel and the Recycle Bin, which keeps deleted files until they are restored or the bin is emptied; Shift+Delete removes a file without sending it there. UNIX was developed at Bell Labs in 1969 by Ken Thompson and Dennis Ritchie. Linux, a free Unix-like system built on the kernel Linus Torvalds released in 1991, comes in distributions such as Ubuntu, Fedora and Debian, and its mascot is the penguin Tux. Android, a Linux-based mobile OS, was bought by Google in 2005, and the first Android phone came out in 2008; Apple's iOS runs the iPhone.
Booting
Booting is starting a computer and loading the OS from disk into RAM. Cold booting starts a computer from power off; warm booting restarts one that is already on, using Restart (in the DOS era, Ctrl+Alt+Del). On power-up the BIOS runs the POST (power-on self-test) to check the hardware, and then the bootstrap loader finds the OS and loads it.
Files and folders
A file is a named collection of data stored on disk; its name ends in an extension after a dot that shows its type, as in report.docx or photo.jpg. Folders, also called directories, hold files and other folders in a tree. The top level is the root directory, written C:\ in Windows and / in Linux, and the path gives a file's full location. The OS organises a disk with a file system, such as FAT32 or NTFS in Windows and ext4 in Linux.
Key facts
- System software (OS, device drivers, translators, utilities) runs the computer; application software (MS Word, browsers, accounting software, games) does the user's tasks.
- Firmware is software stored permanently in ROM or flash, such as the BIOS or UEFI.
- Open source: Linux, LibreOffice, Firefox, Apache; proprietary: Windows, MS Office, macOS; freeware is free of cost, shareware is try first and pay later.
- OS functions: process, memory, file, device and security management plus the user interface; the kernel is the core of the OS, the shell carries user commands to it.
- Real-time OS responds within a fixed time (missiles, air traffic control); time-sharing OS gives each user a slice of CPU time (UNIX); batch OS runs grouped jobs without interaction.
- MS-DOS (1981) used a command line; Windows 1.0 (1985) was a graphical shell; Windows 95 introduced the Start button and taskbar.
- UNIX: Bell Labs, 1969, Ken Thompson and Dennis Ritchie; Linux kernel: Linus Torvalds, 1991; Linux mascot: Tux the penguin.
- Android is a Linux-based mobile OS bought by Google in 2005; the first Android phone came in 2008.
- Cold boot starts from power off, warm boot restarts a running computer; the BIOS runs POST (power-on self-test) at start-up.
- Shift+Delete deletes a file permanently, bypassing the Recycle Bin; the root directory is C:\ in Windows and / in Linux.
Quick revision
Software = system (OS, drivers, translators, utilities) + application (Word, browser); firmware in ROM (BIOS); open source (Linux, Firefox) vs proprietary (Windows, MS Office); OS manages processes, memory, files, devices, security; kernel and shell; CLI vs GUI; batch, time-sharing, real-time, multi-user, distributed OS; MS-DOS 1981, Windows 1.0 1985; UNIX 1969; Linux 1991; Android bought by Google 2005; booting: POST, bootstrap loader; cold vs warm boot.