This about computer virus and how virus harms to our computer.

1. Computer Virus
 What is Computer Virus?
 What do virus do?
 How virus enter your computer?
 How virus enter your computer?
 Type of viruses?
 How to protect your computer from virus
 How you know your computer affected with
virus?
 Malware
 Worms etc.

2. What is Computer Virus?
A computer virus is a malicious piece of computer code
or program designed to spread from device to device. A
subset of malware, these self-copying threats are usually
designed to damage a device or steal data.
Think of a biological virus – the kind that makes you sick.
It’s persistently nasty, keeps you from functioning
normally, and often requires something powerful to get
rid of it. A computer virus is very similar. Designed to
replicate relentlessly, computer viruses infect your
programs and files, alter the way your computer operates
or stop it from working altogether.

3. What do virus do?
 Some computer viruses are programmed to harm
your computer by damaging programs, deleting files,
or reformatting the hard drive. Others simply replicate
themselves or flood a network with traffic, making it
impossible to perform any internet activity. Even less
harmful computer viruses can significantly disrupt
your system’s performance, sapping computer
memory and causing frequent computer crashes.

4. How virus enter your computer?
Even if you’re careful, you can pick up computer
viruses through normal Web activities like:
Sharing music, files, or photos with other users
Visiting an infected website.
Opening spam email or an email attachment.
Downloading free games, toolbars, media players
and other system utilities.
Installing mainstream software applications without
thoroughly reading license agreements.

5. Type of viruses?
Cybercriminals are getting better and better at
stealing our confidential data and viruses that are
being created are evolving rapidly. There are
millions of viruses around the world, but here are
some common types you should be aware of:

6. 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.

7. File-infecting Virus
A virus that attached itself to an executable program.
It is also called a parasitic virus which typically
infects files with .exe or .com extensions. Some file
infectors can overwrite host files and others can
damage your hard drive’s formatting.

8. 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.

9. How to protect your computer from virus
 Don't click on hyperlinks from unknown senders or open email
attachments.
 Use filtering tools to block unsolicited emails, instant messages, and
pop-ups or spam blocking
 Use strong passwords and change them regularly Exercise alert
when downloading records from the Internet. Just download from
confided sources
 Back up records on your PCs routinely utilizing an external hard
drive. Dent keep delicate or hidden data on your PC. In case your
computer gets hacked,
 Scan email attachments before opening it.
 Avoid clicking on pop-up advertisements and get a pop-up blocker
for your web browser.
 When routed to another website, don’t do anything, and
immediately leave the site.
 Install a reliable anti-virus program and always keep it up to date.

10. How you know your computer affected with virus?
A computer virus attack can produce a variety of symptoms.
Here are some of them:
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

11. Malware
Malware is the collective name for a number of
malicious software variants, including viruses,
ransomware and spyware. Shorthand for malicious
software, malware typically consists of code developed
by cyber attackers, designed to cause extensive damage
to data and systems or to gain unauthorized access to a
network.

12. Worms
A computer worm is a type of malware that spreads
copies of itself from computer to computer. A worm
can replicate itself without any human interaction,
and it does not need to attach itself to a software
program in order to cause damage.

13. A Trojan horse
A Trojan horse, or Trojan, is a type of malicious code
or software that looks legitimate but can take control
of your computer. A Trojan is designed to damage,
disrupt, steal, or in general inflict some other
harmful action on your data or network.
A Trojan is sometimes called a Trojan virus or a
Trojan horse virus, but that’s a misnomer. Viruses
can execute and replicate themselves. A Trojan
cannot. A user has to execute Trojans. Even so,
Trojan malware and Trojan virus are often used
interchangeably.

14. Spyware
Spyware is defined as malicious software designed
to enter your computer device, gather data about
you, and forward it to a third-party without your
consent. Spyware can also refer to legitimate
software that monitors your data for commercial
purposes like advertising.

15. Ransomeware
Ransomware is a form of malware that
encrypts a victim's files. The attacker then
demands a ransom from the victim to restore
access to the data upon payment.

16. Rootkits
A rootkit is a collection of computer software,
typically malicious, designed to enable access to a
computer or an area of its software that is not
otherwise allowed (for example, to an unauthorized
user) and often masks its existence or the existence
of other software.

17. BACKDOOR
A backdoor is a means to access a computer system
or encrypted data that bypasses the system's
customary security mechanisms. A developer may
create a backdoor so that an application or operating
system can be accessed for troubleshooting or other
purposes.

18. ANTIVIRUS
Antivirus software is a program or set of
programs that are designed to prevent,
search for, detect, and
remove software viruses, and other
malicious software like worms, trojans,
adware, and more.

19. What does antivirus software do?
Antivirus software helps protect your computer against
malware and cybercriminals. Antivirus software looks at
data — web pages, files, software, applications — traveling
over the network to your devices. It searches for known
threats and monitors the behavior of all programs, flagging
suspicious behavior.
Antivirus software therefore performs three major
functions.
Identifying malicious codes in the system.
Removing them by destroying or isolating them.
Most importantly, protecting your device from getting

20. Farewall
A firewall is a network security device that monitors
incoming and outgoing network traffic and permits
or blocks data packets based on a set of security
rules. Its purpose is to establish a barrier between
your internal network and incoming traffic from
external sources (such as the internet) in order to
block malicious traffic like viruses and hackers.