3 Software
Systems software manage the computer hardware's basic functions and the human/computer interface common to all programs you might run. The most common systems software on desktop computers is the graphical user interface (GUI) of PCs and MacIntosh computers. This software is called the operating system (OS). On PCs it is Windows, and on the Mac and many other computers it is Unix. Application software is the software that provides end-user functionality, such as word processing, spreadsheets, internet browsing, and supports major business processes such as payroll, financial accounting, purchasing, inventory control, manufacturing, and myriad other business tasks. Each of these is an "application." You can buy the software for some common applications such as word processing over the counter in a retail store. Other applications, such as custom software solutions for a particular business, are designed and programmed by personnel locally, often to gain competitive advantage.