Viruses & Antivirus

A computer virus is a harmful program created to damage files, slow down a computer, or steal information. Viruses spread quietly, just like a cold spreads between people.

How Does a Computer Catch a Virus?

A virus usually enters a computer when you open an infected email attachment, download files from unsafe websites, or plug in an infected pen drive. Clicking unknown links can also let a virus inside.

A virus tries to enter through unknown files — antivirus software blocks it

Signs Your Computer May Have a Virus

🐢 The computer runs much slower than usual
🔁 Programs crash or freeze often without reason
📁 Files disappear or become corrupted on their own
🪟 Strange pop-up windows appear repeatedly
💾 The hard disk shows less free space than expected

What is Antivirus Software?

Antivirus software protects a computer from viruses. It scans files for danger and removes harmful programs before they cause damage. Popular antivirus programs include Windows Defender, Norton, and Quick Heal.

How Antivirus Works

Antivirus software checks every file against a list of known virus patterns. If a match is found, it quarantines (locks away) or deletes the harmful file immediately, keeping the rest of the computer safe.

🟢 Tip: Keep antivirus software always updated. New viruses appear daily, and updates teach the antivirus how to recognise them.

Simple Habits to Avoid Viruses

Never open email attachments from unknown senders. Avoid downloading software from unfamiliar websites. Scan any pen drive before opening its files. Keep Windows updated with the latest security patches.

💡 Fun Fact: The first computer virus, called "Creeper," appeared in 1971. It only displayed a playful message: "I'm the creeper, catch me if you can!" Modern viruses are far more dangerous.

✏️ Exercise

Q1. What is a computer virus?

✅ A computer virus is a harmful program that damages files or steals information.

Q2. Name one sign that a computer might have a virus.

✅ Examples: The computer runs slower than usual, programs crash, or files disappear.

Q3. What does antivirus software do?

✅ Antivirus software scans for and removes harmful viruses to protect the computer.

Q4. Name one safe habit that helps avoid viruses.

✅ Examples: Never open attachments from unknown senders, or scan pen drives before use.

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