What is virus..?

A computer virus, much like a flu virus, is designed to spread from host to host and has the ability to replicate itself. Similarly, in the same way that flu viruses cannot reproduce without a host cell, computer viruses cannot reproduce and spread without programming such as a file or document.     

Types of virus 

1. Boot sector virus

This type of virus can take control when you start — or boot — your computer. One way it can spread is by plugging an infected USB drive into your computer.

2. Web scripting virus

This type of virus exploits the code of web browsers and web pages. If you access such a web page, the virus can infect your computer.

3. Browser hijacker

This type of virus “hijacks” certain web browser functions, and you may be automatically directed to an unintended website.

4. Resident virus

This is a general term for any virus that inserts itself in a computer system’s memory. A resident virus can execute anytime when an operating system loads.

5. Direct action virus

This type of virus comes into action when you execute a file containing a virus. Otherwise, it remains dormant.

6. Polymorphic virus

A polymorphic virus changes its code each time an infected file is executed. It does this to evade antivirus programs.

7. File infector virus

This common virus inserts malicious code into executable files — files used to perform certain functions or operations on a system.

8. Multipartite virus

This kind of virus infects and spreads in multiple ways. It can infect both program files and system sectors.

9. Macro virus

Macro viruses are written in the same macro language used for software applications. Such viruses spread when you open an infected document, often through email attachments.

How a virus gets spread in your pc

Computer viruses usually spread in one of three ways: from removable media; from downloads off the Internet; and from e-mail attachments. Although the Internet gets a bad rap as a source of viruses, you're no more likely to contract a virus from the Web than you are from packaged software.
 Any disk, disc, or thumb drive connected or inserted into your computer can be infected with a virus. As long as something is writable, a virus can move from a computer to that disk, disc, or drive. A common tactic used by hackers to gain access to a network is by leaving out a thumb drive with malicious code on it.

What are the signs of a computer virus?

• Frequent pop-up windows. Pop-ups might encourage you to visit unusual sites. Or they might prod you to download antivirus or other software programs.
• Changes to your homepage. Your usual homepage may change to another website, for instance. Plus, you may be unable to reset it.
• Mass emails being sent from your email account. A criminal may take control of your account or send emails in your name from another infected computer.
• Frequent crashes. A virus can inflict major damage on your hard drive. This may cause your device to freeze or crash. It may also prevent your device from coming back on.
  
• Unusually slow computer performance. A sudden change of processing speed could signal that your computer has a virus.
• Unknown programs that start up when you turn on your computer. You may become aware of the unfamiliar program when you start your computer. Or you might notice it by checking your computer’s list of active applications.
• Unusual activities like password changes. This could prevent you from logging into your computer.

Who creates computer viruses  

A computer virus is a type of malicious software that, when executed, replicates itself by modifying other computer programs and inserting its own code. When this replication succeeds, the affected areas are then said to be "infected" with a computer virus.Some people create viruses and malware because they enjoy causing trouble, and making others suffer. Some malware can crash an entire network system and cause system outages for large companies, like banks or production companies. 

Most destructive viruses 

1. ILOVEYOU

2. Code Red

3. Meliss

4. Sasser

5. Zeus

6. Conficker

7. Stuxnet

8. Mydoom

9. CryptoLocker

10. Flashback

How safe from Internet virus

Install an anti-virus program

Whether you are connecting to the internet or not, having reliable protection is the route to go. Anti-virus programs are a minimal investment and are worth the dollars so as soon as you power up that computer, make sure you are protected

Install anti-spyware and anti-malware programs

Many of these programs are free and prevent viruses from doing any damage on your computer. They require continuous running and updating but when used correctly, they serve their purpose

Avoid suspicious websites

A lot of times websites will notify you if you are about to enter a website that attempts to install or run a program on your computer but not always. Avoid websites such as those

Set up automatic scans

Setting up scans to run on your computer daily or weekly is a good idea to get rid of any viruses. This keeps your computer updated and clear of issues.

Watch your downloads

We understand that downloading files from the internet such as music and movies is what so many of us do, but it also gets so many of us in trouble.

Keep update you device

Microsoft Windows ‘Critical Update’ is one example of staying ahead of all the hackers out there. Critical Update is an entire branch of Microsoft that is dedicated to keeping computers free is viruses. Always keep your system updated

Install a firewall

A firewall is a program that screens incoming internet and network traffic. Along with your virus program, it can help prevent unauthorized access to your computer.

Will Resetting your device remove virus?

No,Factory resets don't remove infected files stored on backups: viruses can return to the computer when you restore your old data. The backup storage device should be fully scanned for virus and malware infections before any data is moved back from the drive to the computer.