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How To Guide

How to Install Antivirus Software and Run a First Scan

Protect your computer from viruses, malware, and ransomware. Install antivirus software and perform your first security scan in minutes.

Overview

Antivirus software protects your computer from malicious threats. Windows includes built-in protection, while Mac users may want additional software. This guide covers setup and initial scanning.

Step 1: Windows Defender (Built-In Protection)

Windows 10 and 11 include Microsoft Defender, which provides excellent free protection.

1

Check Windows Defender Status

  • Click Start → Settings → Privacy & Security → Windows Security
  • Click "Virus & threat protection"
  • Verify "Real-time protection" is ON
  • Check last scan date under "Current threats"
2

Update Virus Definitions

  • In Windows Security, click "Virus & threat protection"
  • Under "Virus & threat protection updates", click "Check for updates"
  • Wait for definitions to download (usually takes 1-2 minutes)
  • Confirm "Definitions are up to date"
Pro Tip:

Windows Defender updates automatically, but manually checking ensures you have the latest protection before scanning.

3

Run Quick Scan

  • Click "Quick scan" button
  • Scan typically takes 5-10 minutes
  • Review results when complete
  • Click "Start actions" if threats found
4

Schedule Automatic Scans

  • Windows Security → Virus & threat protection
  • Scroll to "Virus & threat protection settings"
  • Ensure "Real-time protection" and "Cloud-delivered protection" are ON
  • Windows automatically scans when idle

Step 2: Installing Third-Party Antivirus (Optional)

Popular alternatives include Norton, Bitdefender, and Kaspersky. This example uses Bitdefender Free.

1

Download Antivirus Software

  • Visit official website (e.g., bitdefender.com, norton.com)
  • Click "Download Free" or "Free Trial"
  • Save installer to Downloads folder
  • Verify download is from official source only
Warning:

Only download antivirus from official websites. Fake antivirus software is a common scam that actually infects your computer.

2

Run Installer

  • Open Downloads folder
  • Double-click installer file
  • Click "Yes" when User Account Control appears
  • Follow installation wizard
  • Create account if required (usually free)
3

Initial Configuration

  • Antivirus will automatically update virus definitions
  • Accept default settings (recommended for beginners)
  • Enable real-time protection if prompted
  • Windows Defender automatically disables when third-party installed
4

Run First Scan

  • Open antivirus program from system tray or Start menu
  • Click "Scan" or "Quick Scan"
  • Wait for scan to complete (10-30 minutes)
  • Review and quarantine any threats found

Step 3: Mac Antivirus Protection

Macs include built-in security but third-party antivirus adds extra protection.

1

Check Built-In Mac Security

  • System Settings → Privacy & Security
  • Verify FileVault is enabled (encrypts disk)
  • Check Firewall is ON
  • Confirm "Allow apps downloaded from: App Store and identified developers"
2

Install Mac Antivirus (Recommended)

Popular options: Malwarebytes (free), Bitdefender, Norton, Kaspersky.

  • Download from official website or Mac App Store
  • Open .dmg file from Downloads
  • Drag app to Applications folder
  • Open app and grant permissions when prompted
  • System Settings → Privacy & Security → Full Disk Access → Enable for antivirus
3

Run First Mac Scan

  • Open antivirus app
  • Click "Scan" or "Check for threats"
  • First scan may take 30-60 minutes
  • Remove or quarantine detected threats
Mac Security:

While Macs are less targeted than Windows, they're not immune to malware. Antivirus helps detect adware, spyware, and malicious files.

Step 4: Understanding Scan Types

1

Quick Scan

  • Duration: 5-15 minutes
  • Coverage: System files, running programs, common infection locations
  • When to use: Regular weekly checks, after suspicious activity
  • Recommended frequency: Weekly
2

Full Scan

  • Duration: 1-4 hours depending on files
  • Coverage: Every file on computer
  • When to use: First installation, suspected infection, monthly maintenance
  • Recommended frequency: Monthly
3

Custom Scan

  • Duration: Varies by selection
  • Coverage: Specific folders or drives
  • When to use: Check USB drives, scan downloads folder, specific suspicious files
  • How to use: Right-click folder → Scan with [antivirus name]
4

What to Do If Threats Found

  • Quarantine: Antivirus isolates threat so it can't harm system
  • Delete: Permanently removes threat (recommended for most cases)
  • False positive: Legitimate files sometimes flagged, research before restoring
  • Backup first: If unsure, backup important files before removing threats
Multiple Threats Found:

If scan finds many threats, your system may be compromised. Back up important files, run full scan, and consider professional help if problems persist.

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