What is a Computer Virus?
A computer virus is a malicious program that acts like a digital parasite, attaching itself to files or programs and spreading across systems. Once activated, it can delete files, steal data, or crash your device. Viruses often disguise themselves as harmless downloads or email attachments, making them difficult to detect.
10 Types of Computer Viruses Explained
Not all viruses behave the same way. Here’s a breakdown of the most common threats:
1. Resident Virus
- What it does: Lodges in your computer’s memory, activating on startup to infect files.
- Example: CMJ virus (targets .COM files).
- Risk: Slows performance and corrupts critical data.
2. Multipartite Virus
- What it does: Attacks boot sectors and executable files for dual damage.
- Example: Invader virus.
- Risk: Survives even if infected files are deleted.
3. Boot Sector Virus
- What it does: Infects the drive sector that loads your OS, often via USB drives.
- Example: Stoned virus (1980s).
- Risk: Prevents your computer from starting.
4. File-Infecting Virus
- What it does: Attaches to apps or games, corrupting them when opened.
- Example: Cascade virus (caused text to “rain” on screens).
- Risk: Renders software unusable.
5. Macro Virus
- What it does: Hides in document macros (Word, Excel) to spread via email.
- Example: Melissa virus (1999).
- Risk: Rapid spread through attachments.
6. Polymorphic Virus
- What it does: Mutates its code to evade detection.
- Example: Storm Worm (disguised as e-cards).
- Risk: Traditional antivirus tools often miss it.
7. Ransomware
- What it does: Encrypts files and demands payment for decryption.
- Example: WannaCry (2017).
- Risk: Paying doesn’t guarantee data recovery.
8. Spyware
- What it does: Secretly monitors keystrokes, browsing, or financial data.
- Example: CoolWebSearch (browser hijacker).
- Risk: Identity theft and financial fraud.
9. Worm
- What it does: Spreads autonomously through networks or email.
- Example: ILOVEYOU worm ($10 billion in damages).
- Risk: Overloads systems and spreads to contacts.
10. Cryptographic Virus
- What it does: Targets encryption systems to lock data or exploit weaknesses.
- Example: Petya (encrypted hard drives).
- Risk: Even experts struggle to recover data.
How to Protect Your Computer: 10 Actionable Steps
1. Install Antivirus Software
2. Update Software Regularly
- Turn on auto-updates for your OS, browsers, and apps to patch vulnerabilities.
- Visit Microsoft’s Windows Update page for the latest security patches.
3. Avoid Suspicious Links & Attachments
- Don’t open emails from unknown senders or download files from sketchy sites.
4. Enable Firewalls
- Activate your OS firewall (Windows Security or macOS Firewall) and consider a router firewall.
5. Back Up Data
- Follow the 3-2-1 rule:
- 3 copies of data
- 2 local (external drive)
- 1 offsite (cloud storage)
6. Scan USB Drives
- Check external devices with antivirus software before accessing files.
7. Use Strong Passwords & 2FA
- Create unique passwords with a manager like 1Password.
- Enable two-factor authentication (2FA) on critical accounts.
8. Avoid Public Wi-Fi for Sensitive Tasks
- Use a VPN (NordVPN, ExpressVPN) to encrypt connections on public networks.
9. Educate Yourself & Others
- Learn to spot phishing scams and teach family members safe browsing habits.
10. Act Fast If Infected
- Disconnect from the internet, run a full antivirus scan, and restore files from backups.
FAQs: Quick Answers to Common Questions
Q: How do viruses spread?
A: Through email attachments, infected downloads, USB drives, or malicious links.
Q: Are Macs immune to viruses?
A: No—recent threats like Silver Sparrow target macOS. Always use antivirus software.
Q: Can smartphones get viruses?
A: Yes! Android devices are more vulnerable, but iPhones can be compromised via malicious apps.
Q: Is free antivirus enough?
A: For basic protection, yes. Paid versions offer better real-time defense and support.
Q: How often should I back up data?
A: Weekly for personal files; daily for business-critical data.
Final Thoughts
Computer viruses—from sneaky spyware to devastating ransomware—are evolving threats. By understanding how they work and adopting proactive habits (like regular updates, backups, and cautious browsing), you can protect your devices effectively.
Share this guide to help others stay safe too!
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Admin at Sirfal.com – Experienced blogger since 2015, sharing Q&A content and latest job updates.