The hard disk is a permanent information storage unit. When a computer is used, the necessary memory to store user instructions, for the procedures the computer carries out and to run the programs is not permanent: it is called RAM and all the things stored in it are deleted when the equipment is turned off. RAM memory is in charge of storing the operating data the computer needs in order to work but it does not save programs or data files. In fact, RAM memory is the ability to move information; comparing it to human beings, it is the short-term memory, retaining the instant information. The hard disk stores things that are not deleted when the equipment is turned off, as a human being cannot forget his name or the place where he lives. In this storage unit, programs and data files created by applications or programs installed on the computer are saved: text processor and texts produced by it, image editor and images modified by it, sound player and the MP3 it may play, etc.

The hard disk is composed of plates where information is saved through terminals. This storage system is called “analogical magnetic recording”. In the same way, the information stored in it is taken and reproduced by the user. The hard disk is the first link in the storage unit chain composed by CD, DVD, floppy disk, ZIP and USB units.

All computers have a hard disk. That means that you do not need to make clear that you want a computer with that unit because all computers carry one inside them. There are even computers carrying two hard disks to store more information. These are called C and D units by default, when there are two. If the computer has just one hard disk, the letter C is assigned to it and the letter D is used for Compact Disc Unit (CD).

What you need to know when choosing what hard disk you wish to have in your computer is the following:

Storage ability: it is the ability to permanently save information. The storage ability measure unit is the Gigabyte (Gb.) and it is usually called GIGAS. A standard hard disk has 80 Gb. storage, but there are disks of up to 500 Gb. You should not be tempted: most of the times we do not even use 80 Gb.

Speed: it is measured in RPM (revolutions per minute) and it is data transfer speed. That is to say, the more speed you have, the less time the computer will take to access what it is asked to do. However, the more speed, the louder noise the disk will make. Of course the noise is very low and usually it is not heard, no matter how fast the disk may be.

There are three things to do in order to keep the hard disk running properly. One of them is to de-fragment it. When the disk is de-fragmented, it becomes faster. Throughout time, files are fragmented (saved in different places) and the hard disk must gather all its parts before reproducing it. Of course, this process takes time and that is why de-fragmenting the hard disk every two months is convenient for it to operate more efficiently. The second thing to do is to verify the damages on the hard disk. This procedure looks for damages on the files and programs stored on the hard disk and it also seeks failures on the disk physical surface. You can choose the option “repair errors” for the computer to automatically fix what is not working properly. Of course, it will not be able to repair the disk surface, and if an error is found there, a technician should be called. Both procedures, de-fragmentation and hard disk repairing, are carried out choosing the hard disk properties from your operating system desktop. The third thing to do to improve the hard disk performance is to make a back up (a safeguard). This procedure implies storing on an external unit (as a CD or DVD) all data you do not want to lose in case of an inconvenience.