Monitor
The monitor is the piece of computer hardware that displays the video and graphics information generated by the computer through the video card. A monitor, usually connects to either an HDMI, DVI, or VGA port. Other connectors include USB, DisplayPort, and Thunderbolt. Before investing in a new monitor, make sure that both devices support the same type of connection.
hard disk
A hard disk is really a set of stacked disks, has data recorded electro magnetically in concentric circles or “tracks” on the disk. A “head writes or reads the information on the tracks. In 1953, IBM engineers created the first hard disk, which was the size of two refrigerators. A hard disk unit comes with a set rotation speed varying from 4500 to 7200 rpm.
RAM and ROM
RAM (Random Access Memory) and ROM (Read Only Memory) are types of computer memory that provide users with access to information stored on a computer. RAM is the memory available for the operating system, programs and processes to use when the computer is running. ROM is the memory that comes with your computer that is pre-written to hold the instructions for booting-up the computer.
Microprocessor
A microprocessor is the most important unit within a computer. its incorporates the functions of a CPU on a single integrated circuit or a few integrated circuits.

Green & Cloud computing
Green computing is also known as green information technology .it is the environmentally responsible and eco-friendly use of computers and their resources. It reduced resource consumption and proper disposal of electronic waste Cloud computing means storing and accessing data and programs over the Internet instead of your computer’s hard drive. Cloud computing is a type of computing that relies on sharing computing resources rather than having local servers or personal devices to handle applications
Operating System
An Operating System (OS) is an interface between a computer user and computer hardware. An operating system is a software which performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.
BIOS
BIOS (basic input output system) is the program a personal computer’s microprocessor uses to get the computer system started after you turn it on. It also manages data flow between the computer’s operating system and attached devices such as the hard disk, video adapter, keyboard and other.
Software
Software has mainly divided into two Categories: Application software and System software. Applications software is used by end user for specific purpose. Application software are computer programs that allow users to perform specific tasks. These programs are commonly referred to as apps and are usually completely self-contained and commercially produced. System Software (type of computer program) provides a platform to run computer’s hardware and computer application to utilize system resources and solve their computation problem.