Software

Hardware on its own does nothing. Software, a set of instructions, makes it work. Software also acts as an interface between users and the hardware.

System software works directly with the hardware:

• the operating system (OS);
• system utilities, which keep the computer in good order: a disk defragmenter, anti-virus programs, disk formatting tools;
• device drivers: each one lets the OS control a particular device. To use a new printer, for example, the computer needs that printer's driver.

Programming tools help people write software:

• Programming languages. Low-level languages (machine language, made of 0s and 1s, and assembly language, made of short codes) are machine dependent: written for one type of processor. High-level languages such as Python are close to English and machine independent.
• Translators turn programs into machine language. An assembler translates assembly language. A compiler translates the whole program at once, before it runs. An interpreter translates and runs it one line at a time, and is needed every time the program runs.
• IDEs (integrated development environments) combine an editor for writing code and a debugger for finding mistakes.

Application software runs on top of system software, to do tasks for users. It can be general purpose (a spreadsheet like LibreOffice Calc, an image editor like GIMP, a web browser) or customised for one organisation (school management software, accounting software, a company's website).

Software also differs in how it is shared:

• Free and Open Source Software (FOSS) shares its source code, so anyone can study and improve it: Ubuntu, Python, LibreOffice, Firefox.
• Freeware is free to use, but may not share its source code.
• Proprietary software must be bought, and its code is kept secret: Windows, Tally.