The term user interface refers to the standard procedures they the user follows in order to iterate with a computer.In the late 1970s and early 80s, the way users accessed computer systems was very complex.They had to memorize and type a lot of commands just to see the contents of a disk, to copy files or to respond to a single prompt. In fact, it was only experts who used computers, so there was no need for a user-friendly interface.In 1984, Apple produced the Macintosh, the first computer with a mouse and a graphical user interface(GUI).Macs were designed with one clear aim: to facilitate interaction with the computer.A few years later, Microsoft launched Windows, another operating system based on graphics and intuitive tools.Nowadays, computers are used by all kind of people, and as a result there in a growing emphasis on accessibility and user-friendly systems.A GUI makes use of a WIMP environment: Windows, Icons, Menus and Pointer.The background of the screen is called the desktop, which contains labelled pictures called icons. These icons represent files or folders.Double-clicking a folder opens a window which contains program, documents, or more nested folders.When you are in a folder, you can launch a program or document by double-clicking the icon, or you can drag it to another location.When you run a program, your PC opens a window there lets you work with different tools.All the programs have a high with of consistency, with similar toolbars, menu bars, buttons and dialog boxes.A modem OS also provides access to networks and allows multitasking, which means you can run several programs - and do various tasks - at the same time. The most popular operating systems are:The Windows family - designed by Microsoft and used most PCs. The most recent version is Windows 8.Mac OS 2013 created by apple and used on Macintosh computers.Unix 2013 a multi-user system, founf on mainframes and workstations in corporate installations.Linux 2013 open-source software developed under the GNU General Public License. This means anybody can copy its source code, change it and distribute it. It is used in computers, appliances and small devices.Windows Mobile 2013 used on most PDAs and smartphones (PDAs incorporating mobile phones).Palm OS 2013 used on Palm handheld devices.RIM 2013 used on BlackBerry communication devices. Developed by Research In Motion.The Symbian OS 2013 used by some phone makers, including Nokia and Siemens.These computer platforms differ in areas such as device installation, network connectivity or compatibility with application software.