What is Malware?

Malware: What it Means, Common Types, & How to Deal With It

Illustration representing a detected virus and a scan to remove it
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Malware, a shortened combination of the words malicious and software, is a catch-all term for any sort of software designed with malicious intent.

That malicious intent is often theft of your private information or the creation of a back-door to your computer so someone can gain access to it without your permission. However, software that does anything that it didn't tell you it was going to do could be considered malware.

Malware is sometimes called badware and is often used synonymously with many of the common types of malware, listed below.

In legal documents, malware is sometimes referred to as computer contamination so if you ever see that, it's just a fancy way of saying malware.

What are Common Types of Malware?

Though some of these terms can be used to describe software with a legitimate, non-malicious intent, malware is generally understood to exist in one or more of the following forms:

  • Virus: Infects program files and/or personal files
  • Spyware: Software that collects personal information
  • Worm: Malware that can replicate itself across a network
  • Trojan horse: Malware that looks, and may even operate, as a legitimate program
  • Browser hijacker: Software that modifies your web browser
  • Rootkit: Software that gains administrative rights for malicious intent

There are other types of programs, or parts of programs, that could be considered malicious due to the simple fact that they carry a malicious agenda, but the ones listed above are so common that they get their own categories.

Some types of adware, the term for advertisement-supported software, are sometimes considered malware, but usually only when those advertisements are designed to trick users in to downloading other, more malicious, software.

How Does a Malware Infection Happen?

Malware can infect a computer or other device in a number of ways.

It usually happens completely by accident, often times by way of downloading software that is bundled with a malicious application.

Some malware can get on your computer by taking advantage of security vulnerabilities in your operating system and software programs. Outdated versions of browsers, and often their add-ons or plug-ins as well, are easy targets.

Most of the time, however, malware is installed by users (that's you!) overlooking what they're doing and rushing through program installations that include malicious software. Many programs install malware-ridden toolbars, download assistants, system and Internet optimizers, bogus antivirus software, and other tools automatically... unless you explicitly tell them not to.

Another common source of malware is via software downloads that at first seem to be something safe like a simple image, video, or audio file, but in reality is a harmful executable file that installs the malicious program.

See the How Do You Protect Yourself From a Malware Infection? section below for help on preventing these types of infections from happening in the first place.

How Do You Remove Malware?

Aside from the most serious of malware infections, most is removable with some simple steps, although some is easier to remove than others.

The most common types of malware are actual programs like the legitimate software you use everyday. Those programs can be uninstalled, just like anything else, from Control Panel, at least in Windows operating systems.

Other malware, however, is more complex to remove, like rogue registry keys and individual files that can only removed manually. These types of malware infections are best removed with antimalware tools and similar specialized programs.

See How to Scan Your Computer for Viruses & Other Malware for some basic instructions on ridding your computer of malicious software. There are several, completely free, on-demand and offline scanners that can quickly, and often painlessly, remove most types of malware.

How Do You Protect Yourself From a Malware Infection?

Obviously, the smartest way to avoid malware is to take precautions to prevent the malware from infecting your computer or device in the first place.

The most important way to prevent malware from reaching your computer is by making sure you have an antivirus/antimalware program installed and that you have it configured to constantly look for signs of malicious activity in downloads and active files.

Beyond software that automatically keeps an eye out for malware, the most important thing you can do to protect your computer is to change your behavior.

One way is to avoid opening email and other messaging attachments from people or organizations you don't know or don't trust. Even if you do know the sender, make sure that whatever is attached is something you were expecting or can follow up about in another message. One clever way malware is spread is by auto-mailing copies of itself to friends and family in an email contact list.

Avoid allowing malware to take advantage of security vulnerabilities in your programs by making sure you're updating your software when updates are available, especially ones for Windows. See How Do I Install Windows Updates? for more on this if you're not sure what you're doing.

See How to Safely Download & Install Software for a number of additional tips that should help you avoid malware when downloading software.

You might also enjoy Ways You're Probably Screwing Up Your Computer, which is full of other things you should keep in mind to keep your computer safe and working  as it should.

You can learn even more about malware at the ​Lifewire.com Antivirus Software site.

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