A virus can cause harm to a computer, its programs and files stored in it. Lost data can usually be recovered by data recovery programs. A virus may be simple enough to cause the computer to halt, or it may be as complicated as a spyware that sends information back to the creator. Most computer viruses can attach themselves to all types of files used. They commonly attack the boot information of the computer and the hard disk boot sector. The virus is thus able replicate itself when you reboot your computer.

There are three ways in which a computer virus is spread; using removable media, use of downloaded files, and using email attachments. Viruses do not spread by the plain text files of emails, but through files attached to the mails. However, only after the attachment is opened by the user, can the virus become active. Worms and Trojans are also threats, which do not replicate themselves like viruses. They wait for some trigger, and then they proceed to steal information to send back to their creator.

Computer viruses were first seen in the 1980s. They appeared in the mainframes such as UNIVAC 1108 and IBM 370. The viruses made life miserable for the early users by disabling system files, hard drives, and speakers. Anti-virus software started to appear for tackling the Brain virus which attacked the boot sector of PCs. This was probably the first virus to attack PCs. Initially, the anti-virus programs were virus specific, but soon their growing number caused companies to develop full-fledged software packages to remove viruses from computers.

Viruses can cause a complete failure of a computer or server. They can cause identity theft and information loss. They may cause a user’s browser to get redirected. They may also be used to place certain ads and unwanted links on the user’s web-page. Viruses can also affect the boot sector and render the computer useless. But the most damage they can do is when they enter the registry files. The passwords and configuration files contained therein may get stolen. Most anti-virus programs use a list of known viruses and their patterns to detect them. Special anti-virus programs are needed to cleanup computer with specific malware and spyware.

Threats from viruses are constantly changing and regular checks should be done to locate them. The anti-virus programs should be updated frequently, and other notifications about viruses should also be tracked. Information is the most sought after today, and most viruses and trojans are designed to retrieve information. Prevention usually takes the form of periodic backup of files and data, running regular scans, and removing the viruses located in the scans. The anti-virus programs used, should also be used to scan the email attachments prior to download. Recovery is then simply a matter of restoring the backed up files after cleaning up your computer. It is recommended to note the identity of the virus and check the anti-virus program has the capability to deal with it in the future.

If you are looking to clean your pc, it is obvious that something is wrong with it. Your computer may have collected dust due to non-use, but that can be cleaned with a rag, and does not need the advice of experts on the internet. No, there is something more sinister, which you are at a loss, how to tackle all by yourself. Most computer users running Windows Operating Systems face the problem of a virus or a malware attack, and they need some advice on how to remove the culprit and how to do that the easiest way. For most, the easiest way is also the free way.

In order to remove a virus from a computer system, we must first gain some knowledge of virus and malware, and what they can do to a computer system. A computer virus is a set of computer code or a program, written by some programmer for a very specific purpose. Just like you use the word-processor program or the accounting package in your computer, the virus is also a program or a package which your computer runs. The difference between a virus program and other programs is that, whereas the other programs are designed to be a help in increasing your productivity, a virus program generally detracts from your computer’s performance. That is because it is designed to cause damage, such as a complete blockage of operation, computer malfunction, stealing data, and passing over the computer’s control to an external agency.

Well, if it is so harmful, why have the virus running on the system in the first place? And, how did it get in? These are the two questions, answers to which, are known to only you, the computer owner. Some preventive methods, good and clean computer habits, are a must if you want to avoid answering these two extremely awkward questions about computer viruses.

First you should be aware that computer viruses exist, and they cause serious damage. You should use application software from known and reputable sources alone. Any unknown or unfamiliar program should preferably be investigated before use. Programs carried over by LAN, CD/DVD, or USB Sticks should be properly scanned. Visits to unknown internet destinations should be made with extreme care. Firewalls should be put up to block external intrusions.

As a first level of defense, an anti-virus program has no parallel. Running in the background, it keeps a constant vigil over the type of programs you run, and the sites you visit. Several free anti-virus programs exist in the market place along with the paid ones. Most of the paid anti-virus programs allow you to try their programs for free for a certain number of days before you are required to pay up or remove the software from your system. However, it should be understood that the free anti-virus programs lack the full functionality of the paid versions. Some will detect only certain types of a computer virus and not others, while some will detect all, but lack the power to remove them, and some are in between, detecting some and removing some, at the same time warning you about the remaining virus and what the paid version would have done to them.

Just as in a human all sorts of ailments crop up when affected by an attack of virus, so it does for a computer, with an attack of computer viruses. The ailments of the human are, to a greater extent, more complicated than that of the affected computer, but then, the computer is not as complicated a piece of machinery as a human. However, an ailment is always nasty, and for proper and continued functioning of the machinery, the attacking virus has to be expunged from the system as early as possible, to keep the computer clean.

An attack of virus or malware, as it is also known, can destroy the hard disk, or corrupt data, or spy on you, or hand over the control of your system to another person. However, there is no reason for anxiety. There is no need to assume that the whole hard disk is to be wiped clean. When trying to clean the computer, there may be some data loss. But, you may not necessarily lose all the data.

First and foremost, it must be ascertained if you really have an attack of computer virus. Some vital symptoms are sluggishness of operation, inability to access files, browser going off to an unrecognizable site, etc. On the other hand, the hard disks may spin unnecessarily; your computer may act strange or may even lock up.

If you suspect an attack of computer virus, the best process would be to run anti-virus software to clean the computer. Some viruses are clever enough to stop anti-virus software from functioning. For such cases, running the anti-virus from a CD/DVD or a flash drive may be necessary. Investing in good anti-virus software and keeping it enabled in your system always, is prudent.

At this point, it may seem that if anti-virus software is so good, why not have two? This may not be a good idea, since anti-virus software uses up quite a bit of computing power, and two of them might slow your system down to a crawl. Also, most anti-virus programs are not mutually compatible and one may claim the other to be a computer virus!

Anti-virus software is an unavoidable requirement if you are using a Windows Operating System. Good and safe habits can help avoid computer virus attacks, but then people who make their living writing computer virus programs, are always on the lookout to finding new methods of attacking computers. There are several of the security tool virus removal programs available in the market. While some are free to use, others have to be purchased. Most of the free programs will not have the entire capability of the purchased versions.

With the anti-virus software, you will have a choice to select for cleaning up a computer if a virus is discovered. This may range from deleting the infected file, to quarantine it in a safe place, to try and repair the file. The best option would be in a sequential manner to try to repair the file, if possible. Failing this, to quarantine the file for a later try at cleaning it, and ultimately, if all else fails, to delete it from the system.