What Is Adware? Definition, Types, and How to Remove It

Adware is a type of software that displays unwanted advertisements on your device, which is often bundled with free programs. It collects browsing data to serve targeted ads and can slow device performance or act as a gateway to more serious malware.

Adware can be downloaded purposely or hidden in another process, so prevention and clean-up tips are a must. Using ad blockers, downloading antivirus software, visiting legitimate download sites, and minding cybersecurity safety tips are all preventative measures to keep you ad-free.

What is adware?

Adware is often classified as a type of malware because you don't choose to put it on your device. On the other hand, it doesn't destroy the function of your machine or threaten to extort funds from you if you don’t follow a set of directions.

Adware isn’t the advertisements you see on websites, as it has to be downloaded onto your computer or mobile device. However, it may feed your data to those advertisers so you receive targeted ads.

This results in payments from advertisers to adware software developers. The program watches your internet browsing habits and reports back to advertisers so they can show you advertisements that might entice you to purchase their product.

You may accidentally download adware since it can piggyback onto your computer from software you consensually download. It’s often found in free programs like freeware or shareware. This includes free downloads and software trials that you download.

5 types of adware

There are several types of adware, but all arrive in one of two ways: the kind you know you’re downloading and the kind you don’t.

1. Legitimate adware

Also known as advertising-supported software, this usually comes in a software package with a program you want. The developer offers the product for free in exchange for downloading and running their adware. As long as the software remains installed, the adware collects your data and sells it to advertisers.

Legitimate adware might seem like a good trade-off, but it becomes increasingly invasive as ads become more specific and targeted. Your best bet is to pay for the software you want to download. If you’re downloading from a reputable site, you can usually purchase the software without the additional adware tacked on.

2. Potentially unwanted applications

Potentially unwanted applications (PUAs) and potentially unwanted programs (PUPs) are found in legitimate adware and aren’t usually malicious. These types of adware are considered legal because they’re included in the free software download terms and conditions, which you must agree to prior to download and installation.

3. Legal abusive adware

This type of adware is technically legal because it isn’t depositing malware onto your system. However, it can become extremely aggressive with pop-up windows and cause poor machine performance.

It’s considered abusive because of the number of unwanted advertisements forced on you. It can also cause your computer or mobile device to slow down significantly.

4. Legal deceptive adware

Although not explicitly designed to damage systems, this type of adware can expose devices to additional security risks.

Because of this program’s nature, it may unintentionally give your device malicious files, programs, or other forms of detrimental malware. It does this by allowing malware to piggyback onto an adware download and weakening your device’s firewall security so malware might sneak through a hole created by the adware.

5. Illegal malicious adware

Illegal adware includes spyware, ransomware, computer viruses, and other malicious software with the potential to ruin your operating system and extort funds. This is illegal to distribute because of the intent behind its use.

While you wouldn’t willingly consent to downloading this type of program, it may come wrapped up with legitimate adware and free software downloads or get deposited on your device thanks to hackers.

Real-world adware examples

Understanding what adware actually looks like in the wild makes it easier to recognize and avoid.

• Gator (Claria): One of the earliest and most widespread adware programs, Gator was bundled with popular free software in the late 1990s and early 2000s. It tracked browsing habits and served pop-up ads based on the websites you visited, often replacing competitor ads with its own.^[1]
• Fireball: Discovered in 2017, Fireball infected an estimated 250 million devices worldwide. It hijacked browsers and replaced default search engines with fake ones. It could also execute malicious code, making it a serious security risk beyond typical adware.^[2]
• HummingBad: This was a mobile adware first identified in 2016 that targeted Android devices. It installed a persistent rootkit to generate fraudulent ad revenue, and at its peak infected around 10 million Android phones.^[3]

Adware vs. malware: What's the difference?

Adware and malware are often confused, but they're not the same thing.

Malware is an umbrella term for any software designed to damage, disrupt, or gain unauthorized access to a device. Adware is a specific type of malware that focuses on serving you ads and harvesting your browsing data for advertisers. Most adware isn't trying to destroy your system, it's just trying to profit from it.

Here's how they compare:

	Adware	Malware
Primary goal	Serve ads, collect browsing data	Damage, steal, or extort
Examples	Gator, Fireball, DollarRevenue	Ransomware, trojans, spyware
Legality	Often technically legal	Typically illegal
Harm level	Annoying to moderate	Moderate to severe
Self-replicates	No	Sometimes (viruses, worms)

How do you get adware?

Adware is typically downloaded from free software, free plugins, free apps, or free software trials. The terms of service may mention that you’re downloading the adware, or they may slip it in without your knowledge. You can also get an adware infection while downloading pay-to-use software from an untrustworthy site.

For instance, let’s say you want Microsoft Office Suite and find a website offering free downloads. Even though this is legitimate software from a legitimate company, the third-party website offering it for free has installed adware on it.

Once you download and install the program, the adware goes to work collecting your data. The third-party site then makes a commission off every ad shown to you. This is why it’s important to download software only from the creator’s verified website. Better to pay for the software than to expose your personal data.

The second way to get adware is simply by browsing the internet. Webpages are made up of lines of code, and malicious code can be integrated into those strings to wriggle its way into your device.

While this is more prevalent on sketchy websites, a reputable website may undergo a hack that allows the cybercriminal to implant unwanted software into the site’s established code. Either way, malicious code can make its way onto your device via a vulnerability in your browser.

Ensure you’re aware of tips to stay safe online so you can avoid these browsing pitfalls.

How do I know if I have adware?

The most obvious way to know if you have adware is by visual and settings changes. If you’re suddenly inundated with pop-up ads or your browser or browser homepage mysteriously changes, adware is likely present on your system. In short, adware could be to blame if your computer starts acting differently and you haven’t made any changes.

Additional signs of infection include:

• Webpages not displaying correctly in your web browser
• Computer or phone feeling slow or “buggy”
• Computer or phone crashing
• Slow internet connection
• Internet searches redirect to other websites
• Toolbars or browser extensions mysteriously appearing
• Mobile battery draining faster than usual
• Higher than normal mobile data usage

If you’d like to check whether common adware programs are installed on your device, the University of Wisconsin-Madison has a handy reference guide to the 300+ most common forms of adware. You can search to see if these are present on your device.

It’s worth noting that you should not delete anything from your device unless you’re sure it’s an unwanted program. You can follow the removal instructions below or do an internet search for the program you think may be suspicious. Ensure you know everything about the program before deleting it to avoid removing a necessary program or process from your machine.

How do I remove adware?

There are several methods to return your device to its pre-adware state.

Restore from a backup

If you regularly back up your files, you can perform a system restore and bring your computer back to the state before you noticed the adware infection. This method requires preparation and regular backups and may not be the best option if you’re suddenly struck with adware and haven’t performed regular system backups.

Manual removal

Manual removal is an advanced method for people comfortable with their computer’s processes and programs.

Search for specifically named adware on your system and delete it using your computer’s install/uninstall functions. This only works if you know what you’re looking for and are confident you won’t remove something vital to your system.

Adware removal tools

This is the best option for ensuring you aren’t removing viable programs. Legitimate adware removal tools will recognize the adware on your system and remove it for you. This leaves essential system processes intact while cleaning your machine. This is our recommended method for adware removal.

Best adware removal tools

The fastest way to remove adware is with an antivirus scanner. These tools detect and remove adware automatically without risking deleting system files.

If you’re trying to decide between free or paid remover tools, it might boil down to what extras you want. If you’re in the market for antivirus software, choose one that includes malware and adware removal tools. If your main goal is cleaning your machine, you can do that with a free tool. Either way, it depends on your preferences.

How do I avoid adware?

You likely can’t completely avoid adware, but you can reduce your chances (and your headaches) by following these simple steps to avoid adware.

1. Keep patches current

Avoid picking up unwanted adware from malicious sites by patching your software and regularly used programs.

2. Stay legal

That free software download might be enticing, but you could end up paying much more by cleaning a malware-riddled machine.

3. Read the fine print

Remember to read all of the terms and conditions when installing a new piece of free software or a free trial. Adware is often slipped into these free downloads so the developers can recoup revenue.

4. Download from trusted sites

When searching for software you want to download, it’s important to use a reputable site. The original software publisher is usually the safest. You can also download from sites like Ninite, which can bundle your download into one package.

If you’re downloading an app to your smartphone, be sure to use the official app store. For Android devices, this is the Google Play Store, and for iPhones and iPads, this is the Apple App Store. The official app stores scan software applications for different types of malware — including adware — and remove any malware-infected apps so you don’t accidentally download them.

5. Be wary of social engineering scams

Social engineering scams rely on you clicking on a suspicious link. You can avoid unwanted adware by knowing how to recognize and avoid these scams.

6. Read reviews

If you want to download a free piece of software, try an internet search for product reviews. If someone previously found adware in the software, they probably already reported it online.

7. Use antivirus software

Antivirus software is meant to prevent unwanted programs from installing on your device. Make sure you have the best antivirus software (and keep it updated).

8. Use an ad blocker

Services like Total Adblock and NordVPN Threat Protection are just some of the ad blockers that can stop pop-ups, intrusive ads, and even malicious code and files containing adware.

9. Sign up for a data removal service

One way to keep your data private is by investing in a data removal service like DeleteMe. These services will find and remove your personal information from the internet so you can fend off adware. DeleteMe even provides continued removals and privacy reports every three months should any new threats arise.

Bottom line

Adware is intrusive and can sometimes be harmful. These unwanted programs can run on your computer, monitor your activity, and sell the information they collect to advertisers — who can become increasingly aggressive in their pursuit of your money. While not technically illegal, adware feels immoral.

Increase your ability to prevent and remove these nuisances from your machine by staying diligent online. With preventative tools like an ad blocker and clean-up tools like adware removers, you can keep your device’s health at 100% — without worrying about spying companies looking for a way to gain a quick buck. Privacy doesn’t have to be an option.

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