First of all we should know what is a virus and how it work and spread; a software program capable of reproducing itself without the permission or knowledge of the user and usually capable of causing great harm to files or other programs on the same computer. A computer virus is often simply called a virus. The term is commonly used to refer to a range of malware, but a true virus does not need to be harmful. To distribute itself, a virus needs to execute. Viruses often hide themselves inside other programs to be executed.

Few widespread viruses

Some viruses called file viruses which also known as executable viruses. These files have the pieces of code that attach themselves to executable files, driver files or compressed files, and are activated when the host program is run. After activation, the virus may spread itself by attaching itself to other programs in the system, and also carry out the mean activity for which it was programmed.

Most file viruses spread by loading themselves in system memory and looking for any other programs located on the drive. If it finds one, it modifies the program’s code so that it contains and activates the virus the next time it’s run. It keeps doing this over and over until it spreads across the system, and possibly to other systems that the infected program may be shared with. Besides spreading themselves, these viruses also carry some type of destructive constituent that can be activated immediately or by a particular ‘trigger’. The trigger could be a specific date, or the number of times the virus has been replicated, or anything equally trivial.

Some virus is Boot sector virus which affects the boot sector of a hard disk, which is a very crucial part. By inserting its code into the boot sector, a virus guarantees that it loads into memory during every boot sequence. A boot virus does not affect files; instead, it affects the disks that contain them. Though boot viruses still exist, they are rare compared to new-age malicious software. Another reason why they’re not so prevalent is that operating systems today protect the boot sector, which makes it difficult for them to thrive.

Macro viruses infect files that are created using certain applications or programs that contain macros such as Microsoft Word, Excel, PowerPoint, Corel Draw, Adobe Photoshop etc. Since macro viruses are written in the language of the application and not in that of the operating system, they are known to be platform-independent–they can spread between Windows, Mac and any other system, so long as they are running the required application.

An email virus could be a form of a macro virus that spreads itself to all the contacts located in the host’s email address book. If any of the email recipients open the attachment of the infected mail, the virus spreads to the new host’s address book contacts, and then proceeds to send itself to all those contacts as well. Email viruses can infect hosts even by previewing the infected email in a mail client.

Few Steps when we are working on the PC.

1. Microsoft users install Microsoft certified antivirus and update from their website on weekly basis.

2. Visit Microsoft website and install the latest updates.

3. Install anti-virus software from a well-known, reputable company, UPDATE it regularly, and USE it regularly.

4. Use scanning for viruses on a regular basis and configure it to start automatically each time you boot your system. This will protect your system by checking for viruses each time your computer accesses an executable file.

5. Don’t use pirated software CD’s

6. Vigilant about accepting programs or other files during on-line chat sessions: this seems to be one of the more common means that people wind up with virus problems.

7. Do regular backups. Some viruses will erase or corrupt files on your hard drive and a recent backup may be the only way to recover your data.

A true virus cannot spread to another computer without human assistance, so when you download any file or check your email or chat with any body, careful to open any file until you know the sender. My personal feeling is that if an executable file shows up unexpectedly attached to an E-mail, you should delete it unless you can positively verify what it is, who it came from, and why it was sent to you.Spam is still a huge problem. Ninety percent of all e-mail is spam. Don’t click on links claiming to be from your bank – they’re not. And don’t take stock advice that comes into your inbox.

If you view videos from websites, playing a game on a file-sharing network, or using a broadband internet connection, a firewall or anti virus programs is a must, because your computer is online whenever you turned on even you are not using internet. Most of this software has the ability to automatically execute JavaScript, Word macros or any other executable code contained in or attached to a message, I strongly recommended that you disable this feature. Save the attachment to disk and then check it with an up-to-date virus scanner before opening the file.

Make sure your anti-virus software is up to date. Out-of-date anti-virus programs are the No. 1 reason that PCs get viruses. Many programs have auto-update features. Enable them so you don’t have to worry about monitoring the software yourself.