What Is a Computer Virus & How to Avoid Infection in 2024

Kate Davidson
Updated on: August 22, 2024 Chief Editor

Viruses are as old as computers. If your device is acting weird, running slowly, restarting randomly, or doing things on its own without your input, it is likely infected with a virus.

Viruses are a type of malware  — software created for malicious purposes. Specifically, viruses are malware capable of self-replication. I’ll explain more later, but you should know that though there are lots of different threats that fit under the malware umbrella, people often say virus when referring to malware in general.

There can be huge negative consequences for victims of viruses. They can damage your device, steal your personal information, or lock all the info on your computer and demand a cash ransom in order to restore your data. Emails, family photos, contacts, sensitive banking info, and passwords can all be compromised if hackers manage to get a virus onto your system.

Luckily there are ways to avoid computer viruses and recover if you’re already infected. First and foremost, you need to exercise caution while online. Secondly, a good antivirus like Norton is essential for stopping threats before they can activate and safely dealing with any that have already gotten through. All computers come with basic security software installed, but third-party tools are generally more effective and come fitted with more advanced features.

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Computer Virus 101

Just like the flu virus, a computer virus spreads from one host to another (in this case, a computer, not a human). Once a virus has infected a computer, it can be difficult to safely remove.

Rather than coming about through evolution, computer viruses are created by hackers. Usually motivated by personal gain, cybercriminals create viruses to steal data, make money, or simply annoy users out of sheer spite.

The lifecycle of a virus can be divided into 4 stages, the first of which is infection. This covers how the malware gets onto your device. Avenues for infection include malicious email attachments, standalone downloads, or hackers exploiting vulnerabilities in legitimate programs.

Regardless of how an infection occurs, the next step is execution. Many viruses release their malicious payload immediately after they land on a new hard drive, but others are sneakier and lay dormant until certain conditions are met.

In any case, once a virus gets running, it will enter the replication stage, reproducing itself across the infected device. This makes viruses difficult to deal with — you can’t simply delete a file once you discover it’s malicious because by the time that happens, there’ll be far too many instances of the virus. On the other hand, antiviruses can perform complex simultaneous tasks, so they’re much better at dealing with viruses (hence the name).

Once a virus has replicated itself sufficiently, it will activate. Depending on how it’s designed, a newly activated virus could encrypt your data, download additional malware, corrupt essential systems, display annoying and insulting messages, or any number of other things.

Viruses are just one type of malware. Cybercriminals also use worms, rootkits, and other tools to harm their victims. In addition, there are other dangers (namely phishing) that don’t involve any nefarious software, but use social engineering tactics to try to get you to willingly reveal personal info. The threats posed by these threats are quite similar to those posed by viruses, and adopting the right habits to avoid viruses will help keep you safe from other cyber threats as well.

How Do You Get a Virus?

The vast majority of viruses are spread over the internet. You can get infected by clicking on an email attachment, visiting a suspicious website, or downloading a file from a less-than-reputable source. It’s also possible to just be unlucky and end up with a virus if hackers exploit a vulnerability in a legitimate program that you use.

How Do You Know You Have a Virus?

It depends on the virus. Some are very stealthy while others make it very obvious that there’s a problem. If your device is acting unusually in any way, a virus could be the culprit. But in some cases, you’ll need to use an antivirus to definitively determine whether you’re infected.

Here are some signs to look out for that could indicate the presence of a virus:

• Web redirects (clicking a link takes you to the wrong site).
• Slowed performance.
• Unusual pop-ups prompting you to download an antivirus or other program.
• Unauthorized password changes.
• Missing or inaccessible files.
• Mass emails being sent to your contact list without your authority.
• Changes to your homepage or new toolbars on your browser.
• Excessive error messages.
• Computer freezes or crashes.
• Unfamiliar programs starting up when you turn on your computer.

How to Defend Against Computer Viruses

There’s no shortage of new computer viruses and other malware popping up every day, and there’s no single thing you can do to stay safe. That said, there are steps you can take to reduce the odds that you get a virus.

Here are 6 tips that you can use to stay safe:

1. Use an antivirus product. There are many antivirus software tools on the market, each with its own benefits and downsides. Any product worth its salt will detect most threats before they activate and, if you do get infected, will quickly and decisively deal with the virus. Antiviruses will look for suspicious behavior to detect threats, and the best premium antiviruses (like Norton and Bitdefender) also have extras like web protection that will block dangerous sites.
2. Don’t open suspicious email attachments. If you get a strange email from someone you know, contact them to confirm that they actually sent it. If a message promises something that sounds too good to be true or asks you to take immediate action, there’s probably a virus attached or a scam in the works.
3. Don’t click on suspicious pop-ups. Not all pop-ups are dangerous, but if you’re on a sketchy site promising free stuff, chances are that any pop-ups contain viruses or other threats. Whether you’re on a website or your desktop, if you get a pop-up telling you that you have a virus that needs fixing, the pop-up itself is probably the virus. Don’t click on it.
4. Only download software from trustworthy sources. The allure of free apps and movies can be tempting, but the price of a lot of ‘free’ stuff is adding a virus to your device.
5. Back up your files. Use cloud storage to ensure that you always have a copy of your important documents and photos. Should you get a virus that deletes your computer’s files, you’ll have a backup.
6. Avoid giving out personal information online. The more a hacker knows about you, the easier it is for them to get malware onto your system. Though technically distinct from viruses, phishing is another big threat. This is when hackers trick victims into giving out personal information (including credit card details) by creating fake websites and apps. Many antiviruses can detect this type of threat, but caution is always warranted when your personal information is on the line.

What to Do Next to Protect Yourself?

The best solution is to stay vigilant online and install a reputable antivirus program. Take these steps, and you’ll dramatically reduce the risk of getting infected and make it much easier to safely deal with any virus that gets through.

Frequently Asked Questions

What is a virus?

A virus is a type of malware. Specifically, viruses replicate themselves and execute their payload in a unique way. Though they are distinct from worms, rootkits, PUPs, and other types of malware, “virus” is often used as a catch-all term for threats to computers and mobile devices.

How do I remove a virus?

The easiest and most effective way to remove a virus is by using a quality antivirus. Simply run a scan and delete every threat uncovered and you should end up with a virus-free computer. Some viruses can be removed manually, but this usually requires technical knowledge.

Do I have a virus?

To answer this question, you need to ask yourself whether you’re experiencing the common signs of a digital viral infection. There are a lot, but some of the most frequent include web redirects (when you’re sent to a site that isn’t what you clicked on), slow performance, pop-ups, and hacked accounts. If you are indeed infected, you’ll doubtless want to remove the malware with an effective antivirus.

How do I avoid getting a virus?

There are 2 main ways to avoid viruses and other malware: use an antivirus and exercise caution and good judgment while online. The first option is easier and more effective. In addition to removing any threats that have already made their way onto your system, a premium antivirus will use real-time protection to stop viruses before they can land in your hard drive. I still recommend taking steps like avoiding sketchy downloads and refraining from clicking unusual email attachments, but this level of caution is best paired with an antivirus.