Protect Yourself: Learn the Types of Computer Virus

Published: 15 Sep 2025

Imagine your computer suddenly slowing down, files disappearing, or strange pop-ups appearing. This usually happens because of a computer virus, a small program that can harm your system or steal information.

There are different types of computer viruses, like Trojans, worms, and ransomware. Knowing these computer virus examples helps you take the right steps for virus protection and keep your computer safe.

In this article, we’ll learn about types of viruses.

Table of Content

What is a Computer Virus?
How Do Computer Viruses Spread?
Types of Computer Viruses
How to Protect Your Computer from Viruses?
Conclusion
FAQs

What is a Computer Virus?

A computer virus is a harmful program that can damage files, slow down your computer, or steal personal information. It spreads from one computer to another, often without the user knowing. Viruses can cause problems like missing files, slow performance, and strange pop-ups.

Viruses are malicious programs that can damage files, slow down computers, or steal personal information.

Common symptoms of a virus include:

Slow computer performance.
Unexpected pop-ups.
Missing or corrupted files.
Unusual error messages.

Knowing a computer virus definition helps you understand how viruses affect computers and why protection is important.

How Do Computer Viruses Spread?

Computer viruses can spread in many ways, causing damage to your files, stealing information, or slowing down your computer. Understanding how computer viruses spread is important to keep your system safe. Knowing the common virus transmission methods helps prevent infections before they happen.

Viruses often enter your computer through simple actions like opening unsafe files or visiting risky websites. Being careful with downloads and attachments can reduce the risk.

Examples:

Email attachments that contain hidden viruses.
Unsafe downloads from untrusted websites.
Infected USB drives or other external devices.
Malicious websites that automatically install harmful programs.

Types of Computer Viruses

Computer viruses come in many forms, each designed to harm your system in different ways. Knowing the types of computer viruses helps you recognize threats and protect your computer effectively.

Here are some kinds of computer viruses.

File Infector Virus
Macro Virus
Boot Sector Virus
Polymorphic Virus
Resident Virus
Non-resident Virus
Multipartite Viru
Rootkit Virus
Trojan Horse
Worms

Let’s look at them in detail.

File Infector Virus

A file-infecting virus attaches itself to files and spreads whenever the infected file is opened. It can damage programs, corrupt files, and slow down your computer, making it hard to use.

Real-life example: Opening infected software, games, or downloaded files can activate the virus.

Symptoms:

Corrupted or missing files.
Unexpected crashes or system errors.
Slow computer performance.

Knowing file infector virus examples and signs of a file virus can help you detect and remove it early.

Macro Virus

A macro virus hides in documents and spreads when the document is opened. These viruses target macros in programs like Microsoft Word or Excel and can make your files behave strangely.

Symptoms:

Strange macros are running automatically.
Files are behaving weirdly or crashing.
Unexpected messages or actions in documents.

Knowing macro virus examples and macro virus symptoms helps you detect and prevent infections.

Boot Sector Virus

A boot sector virus infects the startup sector of your computer. It can stop your computer from starting normally and make it difficult to access your system.

Symptoms:

Slow booting or failure to start.
Error messages during startup.
Unresponsive system during launch.

Knowing boot sector virus signs is important to recognize one of the dangerous types of computer virus early.

Polymorphic Virus

A polymorphic virus constantly changes its code to avoid detection. It hides from antivirus software by modifying itself, making it hard to remove.

Symptoms:

Repeated infections even after cleaning.
Frequent antivirus alerts.
Slow computer performance.

Knowing polymorphic virus examples and how to use polymorphic virus protection can help keep your system safe.

Resident Virus

A resident virus stays in your computer’s memory and can infect any program you run. Once active, it can cause problems every time you use your system.

Symptoms:

Random program crashes.
Slow computer performance.
Unexpected errors.

Knowing the resident virus definition helps you understand one of the common computer virus types.

Non-Resident Virus

A non-resident virus runs and spreads, but leaves the computer’s memory after execution. Unlike a resident virus, it only affects specific programs or files and does not stay active in memory.

Symptoms:

Only certain programs or files are affected.
Unexpected errors when opening infected files.
No ongoing memory-related issues.

Knowing non-resident virus examples helps you understand this virus type explained clearly.

Multipartite Virus

A multipartite virus attacks in multiple ways by combining file infection and boot sector attacks. This makes it harder to remove because it can spread through different parts of your computer.

Symptoms:

Repeated infections even after antivirus scans.
Slow computer performance.
Corrupted files and startup issues.

Knowing multipartite virus examples helps you recognize one of the more dangerous computer virus types.

Rootkit Virus

A rootkit virus hides in system files and gives hackers secret access to your computer. It’s like a hidden key that lets attackers control your system without your knowledge.

Symptoms:

Hidden or missing files.
Unusual network activity.
Slow or unresponsive system.

Knowing rootkit virus signs helps you identify this dangerous computer virus type early.

Trojan Horse

A Trojan Horse looks like a normal program but carries hidden malware. It seems safe, but once installed, it can harm your computer and steal information.

Symptoms:

Unexpected programs are running without permission.
Data theft or loss.
Slow or unusual computer behavior.

Knowing Trojan virus examples and Trojan virus symptoms helps you detect and avoid this type of malware.

Worms

A worm is a virus that can self-replicate and spread across networks without needing you to open any files. It moves on its own, infecting multiple computers quickly.

Symptoms:

Slow network performance.
Many copies of files appear unexpectedly.
Unexpected system crashes.

Knowing computer worm examples helps you understand different worm virus types and how they spread.

How to Protect Your Computer from Viruses?

Protecting your computer from viruses is important to keep your data safe and your system running smoothly. Computer virus protection involves simple but effective steps that prevent infections.

Keep your antivirus software updated regularly.
Avoid suspicious downloads, emails, or websites.
Regularly back up important files.
Use strong passwords and enable firewall protection.

Following these steps shows you how to prevent viruses and stay safe online.

Conclusion

Understanding the types of computer viruses is important to keep your computer safe and protect your personal information. By knowing how viruses work and what symptoms to watch for, you can take the right steps for virus protection tips.

Stay vigilant, update your software, avoid risky downloads, and regularly back up your files to ensure your system remains secure and healthy.

Keep your computer safe, update your antivirus, avoid risky files, and follow these virus protection tips today!

FAQs

Still have questions? Start protecting your computer today with these simple virus protection tips!

What is the most common type of computer virus?

The most common type of computer virus is the Trojan Horse. It looks like a normal program, but it can steal data or harm your computer.

How can I tell if my computer has a virus?

You can tell if your computer has a virus by looking for slow performance, strange pop-ups, or missing files. Unexpected crashes or unusual network activity are also common signs.

Can a virus delete my files permanently?

Yes, a virus can delete your files permanently. Some viruses corrupt or erase files, making them unrecoverable without backups.

How do Trojan horses work?

Trojan horses work by disguising themselves as safe programs. Once installed, they can steal data, damage files, or give hackers access to your computer.

Are Mac computers safe from viruses?

Mac computers are less targeted but not completely safe from viruses. They can still get infected through unsafe downloads, email attachments, or malicious websites.

What is the difference between a virus and a worm?

A virus needs a file or program to spread, while a worm can replicate and spread on its own through networks. Worms usually move faster and can infect many computers without user action.

Can antivirus software remove all types of viruses?

No, antivirus software cannot remove all types of viruses. Some viruses, like polymorphic viruses or rootkits, can hide or change, making them harder to detect and remove.