A computer virus is a harmful computer program. It can enter a computer without the user’s knowledge and can cause problems.
A virus can copy itself and spread from one file or computer to another.
Simple Example
Suppose you have a file on your computer. If that file has a virus and you open it, the virus may become active and affect other files.
How Does a Computer Virus Enter a Computer?
A virus can enter a computer in many ways.
1. Through Email
Sometimes we receive an email with an unknown file or attachment.
If the attachment contains a virus and we open it, the computer may get infected.
Example:
You receive an unexpected email with a file → You open the file → Virus may enter the computer.
2. Through USB
A virus can also spread through a USB drive.
If an infected USB is connected to a computer and an infected file is opened, the virus may spread to that computer.
USB → Infected File → Computer
3. Through Unsafe Downloads
Downloading programs, games, or files from unknown websites can be risky.
Some files may contain viruses.
So, we should download software from trusted and official sources.
4. Through Infected Files
A virus can be hidden inside a file or program.
When the user opens or runs that file, the virus may start working.
5. Through Fake Links
Sometimes we receive strange links in emails, messages, or websites.
Clicking unsafe links can lead to harmful downloads or fake websites.
What Can a Virus Do?
A computer virus can cause different problems.
1. It can damage files
Some viruses can change or damage important files.
2. It can slow down the computer
The computer may become slower than usual.
3. It can delete files
Some harmful programs can delete or modify files.
4. It can show unwanted messages
A virus may cause strange pop-ups or messages to appear.
5. It can make programs stop working
Some infected programs may crash or behave incorrectly.
6. It can spread
One infected file can sometimes infect other files.
Common Signs of a Virus
A computer may have a virus or other malware if:
- The computer suddenly becomes very slow.
- Unknown programs appear.
- Strange pop-ups appear.
- Files are changed or missing.
- Programs stop working properly.
- The browser behaves strangely.
- The computer shows unusual errors.
Types of Computer Viruses
There are different types of computer viruses.
1. File Virus
It infects computer files and programs.
2. Boot Virus
It affects the part of a computer that helps it start.
3. Macro Virus
It can infect certain documents, especially documents that use macros.
4. Resident Virus
It can stay in the computer’s memory and infect files when certain actions happen.
How Can We Protect Our Computer?
We can follow some simple steps.
1. Use Antivirus
Install and keep trusted antivirus/security software updated.
2. Keep Windows Updated
Always install important security updates.
3. Do Not Open Unknown Files
Do not open files received from unknown or suspicious people.
4. Download From Trusted Websites
Download programs and apps from official or trusted sources.
5. Be Careful With USB Drives
Do not open unknown files from an unfamiliar USB drive.
6. Do Not Click Suspicious Links
Think before clicking strange links in emails or messages.
7. Keep a Backup
Keep copies of important files in a safe place.
Virus and Antivirus
Virus: A harmful program that can cause problems on a computer.
Antivirus: A security program that helps detect, block, and remove viruses and other malware.
So, we can remember:
Virus = Harmful
Antivirus = Protection
Simple Real-Life Example
Imagine that you download a game from an unknown website.
The game looks normal, but it contains a virus.
When you run the game:
Download → Open the file → Virus becomes active → Computer may have problems
This is why we should be careful about what we download and open.