1. What is a Computer?A computer is an electronic device that manipulates information, or "data." It has theability to store, retrieve, and process data. You can use a computer to type documents,send email, and browse the internet. You can also use it to handle spreadsheets,accounting, database management, presentations, games, and more.Computers SimplifiedFor beginning computer users, the computer aisles at an electronics store can be quitea mystery, not to mention overwhelming. However, computers really arent thatmysterious. All types of computers consist of two basic parts:Hardware is any part of your computer that has a physical structure, such as thecomputer monitor or keyboard.Software is any set of instructions that tells the hardware what to do. It is whatguides the hardware and tells it how to accomplish each task. Some examples ofsoftware are web browsers, games, and word processors such as Microsoft Word.what are the two components of computer?1.hardware Your PC (Personal Computer) is a system, consisting of manycomponents. Some of those components, like Windows XP, and all your otherprograms, are software. The stuff you can actually see and touch, and would likelybreak if you threw it out a fifth-story window, is hardware.Not everybody has exactly the same hardware. But those of you who have a desktopsystem, like the example shown in Figure 1, probably have most of the componentsshown in that same figure. Those of you with notebook computers probably have

2. most of the same components. Only in your case the components are all integratedinto a single book-sized portable unit.The system unit is the actual computer; everything else is called a peripheral device.Your computers system unit probably has at least one floppy disk drive, and one CDor DVD drive, into which you can insert floppy disks and CDs. Theres another diskdrive, called the hard disk inside the system unit, as shown in Figure 2. You cantremove that disk, or even see it. But its there. And everything thats currently "in yourcomputer" is actually stored on that hard disk. (We know this because there is noplace else inside the computer where you can store information!).The floppy drive and CD drive are often referred to as drives with removable mediaor removable drives for short, because you can remove whatever disk is currently inthe drive, and replace it with another. Your computers hard disk can store as muchinformation as tens of thousands of floppy disks, so dont worry about running out ofspace on your hard disk any time soon. As a rule, you want to store everything youcreate or download on your hard disk. Use the floppy disks and CDs to send copies offiles through the mail, or to make backup copies of important items.Random Access Memory (RAM)Theres too much "stuff" on your computers hard disk to use it all at the same time. 3. During the average session sitting at the computer, youll probably use only a smallamount of all thats available.The Hard DiskAll of the information thats "in your computer", so to speak, is stored on yourcomputers hard disk. You never see that actual hard disk because its sealed inside aspecial housing and needs to stay that way. Unlike RAM, which is volatile, the harddisk can hold information forever -- with or without electricity. Most modern harddisks have tens of billions of bytes of storage space on them. Which, in English,means that you can create, save, and download files for months or years withoutusing up all the storage space it provides.The MouseObviously you know how to use your mouse, since you must have used it to get here.But lets take a look at the facts and buzzwords anyway. Your mouse probably has atleast two buttons on it. The button on the left is called the primary mouse button, thebutton on the right is called the secondary mouse button or just the right mousebutton. Ill just refer to them as the left and right mouse buttons. Many mice have asmall wheel between the two mouse buttons, as illustrated in Figure 3.The KeyboardLike the mouse, the keyboard is a means of interacting with your computer. Youreally only need to use the keyboard when youre typing text. Most of the keys on thekeyboard are laid out like the keys on a typewriter. But there are some special keyslike Esc (Escape), Ctrl (Control), and Alt (Alternate). There are also some keys acrossthe top of the keyboard labeled F1, F2, F3, and so forth. Those are called the functionkeys, and the exact role they play depends on which program you happen to be usingat the moment. 4. softwareSoftware is the general term for information thats recorded onto some kind ofmedium. For example, when you go to the video store and rent or buy a tape orDVD, what youre really getting is the software thats stored on that tape ordisk. Your VCR or DVD player are hardware devices that are capable ofreading the software from a tape or disk and projecting it onto your TV screen,in the form of a movie.Your computer is a hardware device that reads software too. Most of thesoftware on your computer comes in the form of programs. A program consistsof "instructions" that tell the computer what to do, how to behave. Just as thereare thousands of albums you can buy on CD for your stereo, and thousands ofmovies you can buy to play on your VCR or DVD player, there are thousandsof programs that you can buy to run on your computer.Some general kinds of application software include:*Productivity software, which includes word processors, spreadsheets, andtools for use by most computer users*Presentation software*Graphics software for graphic designers*CAD/CAM software*Specialized scientific applications*Vertical market or industry-specific software (for example, for banking,insurance, retail, and manufacturing environments)