Types of Software

Software is a set of instructions, called a program, that tells the computer hardware what to do. Without software the hardware is just idle machinery. Software is broadly classified into three types — system software, utility software, and application software — and there is also the important modern idea of open-source software.

1. System software. System software is the set of programs that control and manage the basic working of the computer itself and provide a platform on which other programs run. It works quietly in the background, between the user's applications and the hardware. The main kinds are:

• Operating system (OS). The most important system software. It starts the computer, manages the hardware (CPU, memory, storage, and devices), runs the user's programs, manages files, and provides the interface through which the user interacts with the computer. Without an operating system, a computer cannot function. Well-known operating systems include those for desktop computers and those for mobile phones.
• Language translators. Programs that convert a program written by a human (in a programming language) into the machine language the computer understands. The three types are the compiler (translates the whole program at once), the interpreter (translates and runs the program line by line), and the assembler (translates assembly language into machine code).
• Device drivers. Small programs that let the operating system communicate with a particular piece of hardware, such as a printer or a scanner.

2. Utility software. Utility software (also called service programs) is a kind of system-support software that performs specific maintenance and housekeeping tasks to keep the computer running smoothly, safely, and efficiently. It is not used to create a document or do a business calculation; it looks after the computer. Examples include:

• Antivirus software, which detects and removes viruses and other harmful programs.
• Disk cleanup and disk defragmenter tools, which free up space and reorganise files on the disk so it works faster.
• Backup software, which makes safe copies of important data.
• File compression (zip) tools, which reduce the size of files so they take less space and are easier to send.

3. Application software. Application software is a program written to help the user do a specific real-world task — the actual work the user bought the computer to do. It is what most people mean when they simply say "software." Application software is of two broad kinds:

• General-purpose (packaged) software, ready-made and sold to the general public for common tasks — for example, word-processing software (to type letters and reports), spreadsheet software (to work with numbers, tables, and calculations, widely used in business and accounting), presentation software (to make slide shows), database software (to store and retrieve large collections of records), and web browsers (to view websites).
• Special-purpose (custom/tailor-made) software, written specially for one organisation's particular need — for example, a bank's core-banking software, a shop's billing and inventory system, or a school's examination-management software.

4. Open-source software. Open-source software is software whose source code (the human-readable program instructions) is made freely available to everyone, so that anyone may study it, use it, change it, and share it, usually free of cost, under an open licence. This is the opposite of proprietary (closed-source) software, whose source code is kept secret by the company that owns it and which usually must be paid for. …