functions of CPU
The CPU (Central Processing Unit) – which is also called microprocessor or processor – is in charge of processing data. How it will process data will depend on the program. The program can be a spreadsheet, a word processor or a game: for the CPU it makes no difference, since it doesn’t understand what the program is actually doing. It just follows the orders (called commands or instructions) contained inside the program. These orders could be to add two numbers or to send a piece of data to the video card, for example.
When you double click on an icon to run a program, here is what happens:

1. The program, which is stored inside the hard disk drive, is transferred to the RAM memory. A program is a series of instructions to the CPU.
2. The CPU, using a circuit called memory controller, loads the program data from the RAM memory.
3. The CPU also controls all applications and navigation on the computer..
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defination of information technology

Definition

INFORMATION TECHNOLOGY

· the branch of engineering that deals with the use of computers and telecommunications to retrieve and store and transmit information

· Information technology (IT), as defined by the Information Technology Association of America (ITAA), is "the study, design, development ...

· the practice of creating and/or studying computer systems and applications; the computing department of an organization

· (IT) The application of computer, communications and software technology to the management, processing and dissemination of information.

· Any equipment or interconnected system or subsystem of equipment, that is used in the automatic acquisition, storage, manipulation, management, movement, control, display, switching, interchange, transmission, or reception of data or information. ...

· Includes all matters concerned with the furtherance of computer science and technology and with the design, development, installation, and implementation of information systems and applications [San Diego State University]. ...

· The term "IT" encompasses the methods and techniques used in information handling and retrieval by automatic means. The means include computers, telecommunications and office systems or any combination of these elements.

· (IT)- The scientific, technological, and engineering disciplines and the management technologies used in information handling, communication, and ...

· A contract for the acquisition of goods or services related to information technology: computer hardware, software licenses, software development, and maintenance of hardware and software.

· The use of computers and other electronic means to access and process large quantities of data.

· The entire array of mechanical and electronic devices which aid in the storage, retrieval, communication, and management of information--from ...

· Includes both hardware and software. Use this term when the use of information technology is the underlying driver of the "interesting" feature or of the organization's profitability or productivity. ...

· All electronic information processing hardware and software, including maintenance, telecommunications and associated consulting services.broad term that can refer to anything from mainframes to PDAs; any technology that moves information (voice, video, or data)The industry or discipline involving the collection, dissemination, and management of data, typically through the use of computers.

OPERTING SYSTEM

OPERATING SYSTEM

An operating system (commonly abbreviated to either OS or O/S) is an interface between hardware and user; an OS is responsible for the management and coordination of activities and the sharing of the resources of the computer. The operating system acts as a host for computing applications that are run on the machine. As a host, one of the purposes of an operating system is to handle the details of the operation of the hardware. This relieves application programs from having to manage these details and makes it easier to write applications. Almost all computers (including handheld computers, desktop computers, supercomputers, video game consoles) as well as some robots, domestic appliances (dishwashers, washing machines), and portable media players use an operating system of some type. [1] Some of the oldest models may however use an embedded operating system, that may be contained on a compact disk or other data storage device.

Operating systems offer a number of services to application programs and users. Applications access these services through application programming interfaces (APIs) or system calls. By invoking these interfaces, the application can request a service from the operating system, pass parameters, and receive the results of the operation. Users may also interact with the operating system with some kind of software user interface (UI) like typing commands by using command line interface (CLI) or using a graphical user interface (GUI, commonly pronounced