What Is a Computer Virus and How Does It Work?
A computer virus is designed to infect programs & files with malicious code, changing how a computer operates and spreading across systems.
Free antivirus is your first step to online freedom
We believe everyone has the right to be safe online, which is why we offer our award-winning free antivirus to millions of people around the world.
Also available for Mac, Android, and iOS
Also available for PC, Android, and iOS
Also available for Mac, Android, and PC
Also available for PC, Mac, and iOS
2022
Top Rated
Top Rated
2022
Best Protection
Best Protection
Award-winning Antivirus
Catch even new & emerging threats
435+ million users worldwide
We have 30+ years of experience
Get free antivirus that comes with advanced privacy and security tools
Avast Free Antivirus is more than just an antivirus — it also includes these specialist tools:
6 layers of security
Effortlessly run smart scans on software, files, and apps to find vulnerabilities, plus analyze suspicious files in the cloud, get threat alerts, and more.
Easy to install and use
It only takes a moment to install Avast Free Antivirus and once it’s done, it’ll run quietly in the background, protecting you against viruses and other malware in real time, 24/7
Wi-Fi network security
Connect safely to any Wi-Fi network, even unsecured public networks, plus see who’s using your home Wi-Fi and block any intruders with a click.
Protection against ransomware attacks
Protect your information. Don't let your personal photos, files, and documents fall victim to hackers using ransomware.
Complete protection for all your devices
Our most advanced protection is your toughest defense against viruses, ransomware, zero-day threats, Wi-Fi vulnerabilities, and more.
Choose a VPN for true online privacy
Block ISPs from tracking your activity, stop geo-restrictions from content providers, and ensure public Wi-Fi is safe with Avast’s Virtual Private Network (VPN).
Enjoy more storage space and a faster device
Reclaim gigabytes of storage space and get your device working like new by removing junk like leftover files, bloatware, and unwanted programs. Avast Cleanup also updates your software automatically, hibernates resource-draining apps, and more.
It’s so easy to install — switching to Avast takes seconds
You can start using Avast’s award-winning antivirus immediately. It’s quick and easy to install, and gives you all the protection you need to live your online life securely. And it’s totally free — so give it a try right now.
Avast has over 435 million users worldwide
The UI for your software - amazing. Great work over the years. Can't say enough good things!
Ryan R.
Thank you, Avast, for the excellent work you do. I run your antivirus software on both my Mac OS X and my Windows machines. You have the best products on the market, period.
Eric S.
I’ve been using Avast for over a year and have found it one of the best free software protection devices on the market.
Daryl C.
“The well-known security specialist Avast received a total of three awards for its outstanding performance ... shows how reliably and securely the security software renders its service...”
Awarded Top-Rated Product 2022
by AV-Comparatives
by AV-Comparatives
Get privacy and performance tips, straight from the experts
What is a VPN & How Does it Work?
What is a VPN? What does it do? How does it work? And how can you use a VPN? Learn all about a VPN's definition and uses in our guide.
How to Increase Your Internet Speed Right Now
Wondering why your internet speed is slow? Learn how to improve your internet connection right now, whether you're on Wi-Fi or Ethernet.
What Is Hacking?
We all have some concept of hacking - but do you really know what it is? Read our full hacking definition here.
How to Block Websites on Google Chrome
Learn how to block websites on Google Chrome to stop you or anyone else from accessing them from your computer or phone.
TCP vs UDP: What’s the Difference and Which Protocol Is Better?
TCP drives reliable data transfers while UDP prioritizes speed and efficiency. Read more to understand the differences between TCP vs UDP.
How to Clean Your Computer Screen Without Damaging It
Cleaning your computer screen can be a delicate process. Follow our simple guide to learn how to get a clean screen and laptop monitor.
How to Find Out an Unknown Caller’s Number
Receiving calls from an unknown number can be frustrating. Learn how to find out who is calling you from an unknown number here.
How to Fix the Blue Screen Of Death (BSOD) on Windows 10 and 11
Seeing the blue screen of death on your Windows computer can be devastating. Understand the causes and learn how to fix the BSOD.
Keeping people safe & secure around the world
Using real-time intelligence from over 435 million Avast users, we prevent more than 66 million threats every day.
