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
2024
Top Rated
Top Rated
2024
Best Protection
Best Protection
Award-winning Antivirus
Catch even new & emerging threats
Hundreds of millions of users worldwide
We have 30+ years of experience
2022
Top Rated
Top Rated
Get it for free!
Free download
Free download
Download freefrom Google Play Download free
from the App Store
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 help 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, helping to protect you against viruses and other malware in real time, 24/7.
Wi-Fi network security
Connect more safely to any Wi-Fi network, even unsecured public networks, plus see who’s using your home Wi-Fi and help block intruders with a click.
Protection against ransomware attacks
Help protect your information. Don't let your personal photos, files, and documents fall victim to hackers using ransomware.
Comprehensive 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 more online privacy
Help block ISPs from tracking your activity, help avoid geo-restrictions from content providers, and ensure public Wi-Fi is safer 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 hundreds of millions of users worldwide
I have used Avast for a few years. The protection is the best for the money. I also cover my phones with Avast and I haven’t had any problems yet.
Carol J.
2023-09-12
I have used Avast for many years. The reason is very simple: you offer a great free version that actually works. This lets me afford the other amazing services you offer when needed, like Avast Cleanup.
James M.
2023-08-29
I've used Avast Free Antivirus on my computers, tablets, and smart phones for many years. It updates frequently and automatically. It automatically scans and protects me from malicious web sites. It does what I need. What more could I ask?
OB
2023-06-10
“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 2023
by AV-Comparatives
by AV-Comparatives
Get privacy and performance tips, straight from the experts
What Is a VPN and How Does It Work?
You can use a VPN connection to protect online privacy and access content. Learn how a VPN works, what VPN means, and the benefits of a VPN.
Why Is My Internet So Slow & How to Speed It Up
Wondering why your internet is so slow? Learn how to speed up your internet connection & make your download speeds faster.
What Is Hacking?
We all have some concept of hacking - but do you really know what it is? Read our full hacking definition here.
What Is the Dark Web and How to Access It?
The dark web isn't indexed by search engines. Learn how to access the dark web with Tor browser & get black net safety tips.
How to Delete or Deactivate Your Instagram Account
Find out how to permanently delete Instagram or deactivate your account on your phone or computer with this step-by-step guide.
How to Clear the Instagram Cache on Your Device
Learn how to clear the Instagram cache on your iPhone or Android. Easily delete app data using up storage without deleting IG.
How to Identify WhatsApp Scams
Learn to spot WhatsApp scams and fraudsters by recognizing the red flags and scam types.
SSID: What It Means and How to Find Yours
What is SSID and how do you find it on Mac, Windows, iPhone, and Android? Find out all you need to know in this simple guide.
Keeping people around the world safer & more secure
Using real-time intelligence from hundreds of millions of Avast users, we prevent more than 66 million threats every day.
© 2025 Gen Digital Inc.
