Malware is malicious software that is built to attack your device, spy on you, or steal your data. A virus is only one kind of malware.
I have written about antivirus tools and online safety for over 12 years. During that time, I have seen threats change a lot. Old viruses used to erase files. Today, most malware quietly steals your passwords.
What Is Malware?
Malware is any software made to harm a device, steal information, or perform actions without your consent. It may run in the background, so you might not notice it at first.
For example, a fake app may look like a normal photo editor. Once installed, it may ask for access to your contacts, files, or messages. If the app misuses that access, your private data could be at risk.
Malware does not always affect your computer. Some types focus on stealing passwords, tracking your activity, or showing unwanted ads.
Also, malware can affect both home users and businesses. A single infected device may put saved files, email accounts, and other connected services at risk.
Verizon’s 2026 Data Breach Investigations Report found that 73% of ransomware victims had an infostealer infection or a leaked login in the year before the attack. So a small, quiet infection today can become a big issue tomorrow.
Types of Computer Viruses
Here are the main types you should know about.
1. Boot Sector Virus
A boot sector virus infects the master boot record (MBR) of a storage device. It activates when the computer starts, before the operating system loads. This makes it hard to detect and remove without specialized tools.
2. Browser Hijacker
This malware changes your web browser settings without your permission. It may change your default search engine or homepage or add unwanted ads. It often redirects you to malicious websites to collect personal data.
3. Web Scripting Virus
A web scripting virus uses harmful scripts, often written in JavaScript, to target weak spots in websites or browsers. It can steal cookies, hijack sessions, or send you to unsafe sites.
4. Resident Virus
A resident virus hides in system memory. It can run harmful actions all the time and affect files as they are opened or closed. As a result, it can slip past normal file scans.
5. Polymorphic Virus
This virus changes its code each time it infects a new file or system. That makes it hard for antivirus programs that rely on known signatures to catch it.
6. File Infector Virus
A file-infecting virus attaches itself to executable files. It activates when you run the infected file. It often causes corruption or system faults.
7. Multipartite Virus
A multipartite virus spreads in more than one way, such as through boot sectors and executable files. This makes removal complex and helps it resist antivirus programs.
8. Macro Virus
A macro virus is written in the macro language of tools like Microsoft Word or Excel. It triggers when you open an infected document. It often spreads through email attachments.
Difference Between Malware and a Virus
The main difference is that ‘malware’ is the broad term, while a ‘virus’ is one type of malware.
| Malware | Computer virus |
|---|---|
| Includes many types of harmful software | Is one specific type of malware |
| May steal data, spy on users, or lock files | Attaches to files or programs and can spread |
| Includes worms, Trojans, spyware, and ransomware | Usually needs an infected file or program to spread |
| Can affect many types of devices | Can affect devices that run vulnerable software |
Think of it like cars and trucks. Every truck is a vehicle, but not every vehicle is a truck. In the same way, every virus is malware, but not all malware is a virus.
Signs Your Device May Have Malware
Watch for these warning signs:
- Your device suddenly runs slowly or gets hot.
- Your battery drains much faster than before.
- You see pop ups or ads when you are not browsing.
- Your browser homepage or search engine changes by itself.
- You find apps you never installed.
- Friends say they get odd messages from your accounts.
One sign alone may not mean much. However, multiple signs together deserve a closer look.
How to Check for Malware on Mac
Many Mac owners believe their computer cannot get malware. That is not true. Sophos data shows that infostealer attacks on Macs grew by more than 17% year over year, and a family called AMOS was behind almost half of the Mac stealer reports in late 2025.
The good news is that your Mac has built-in security measures. Gatekeeper and XProtect work in the background. Still, you can add your checks. Here is how to check for malware on Mac in six steps.
- Update macOS: Open System Settings, go to General, and choose Software Update. Updates fix the holes that malware uses.
- Open Activity Monitor: Find it in Applications, then Utilities. Look for apps that use a lot of CPU and that you do not know. Search the name online before you close anything.
- Review your apps: Open the Applications folder and delete anything you did not install.
- Check Login Items: In System Settings, open General, then Login Items. Malware often hides here so it can restart with your Mac. Remove anything strange.
- Check your browser extensions: Remove any extension you do not use or trust.
- Run a scan: Use a trusted antivirus tool to scan your whole drive. Choose a well known brand with good test results.
If you find malware, delete the app and empty the trash. Next, restart your Mac. If the problem stays, start in safe mode and scan again. On a Mac with Apple Silicon, shut down, then hold the power button until startup options appear. On an Intel Mac, restart and hold the Shift key.
Thereafter, change the passwords for your email, bank, and Apple account. In my experience, this last step is the one people skip, yet it matters most. A stealer may already hold your logins.
How to Remove Malware from Android
Android phones are a common target because there are so many of them. Fortunately, you can clean an infected phone in a few steps.
First, a warning. Do not search the Play Store for a random “virus cleaner.” Some of those apps are fake and add to the problem.
- Run Google Play Protect: Open the Play Store, tap your profile icon, and choose Play Protect. Then tap Scan. Also check that “Scan apps with Play Protect” is on. Some users turn it off by mistake.
- Find the bad app: Go to Settings, then Apps. Look for apps you do not know, or apps that appeared right when the trouble began.
- Remove admin rights: Some malware gets device admin access, so you cannot delete it. Open Settings, search for “Device admin apps”, and switch off the suspect app.
- Uninstall the app: Go back to Settings, then Apps, and choose Uninstall.
- Use Safe Mode if needed: If the app will not go away, hold the power button, then press and hold “Power off” until “Reboot to safe mode” appears. Tap OK. In Safe Mode, third-party apps cannot run, so you can delete the stubborn one. Restart to leave Safe Mode.
- Factory reset as a last step: If nothing works, back up your photos and contacts, then reset the phone. Be careful to restore only from a backup you trust.
Afterward, change your key passwords from a clean device. Also review which apps have access to your camera, messages, and location.
You can reduce the risk by keeping your software updated, checking app permissions, avoiding unsafe downloads, and backing up your files.
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