Adware: What Is It and How Do I Protect Against It?

Janis von Bleichert
Last update
5. Sep 2023

Is your computer slower than usual? Do pop-ups open, even if you're not surfing the web? If either or both of these are the case, you most likely have an adware infection. In this guide, we'll explain what adware is, how you can prevent future infections, and what you'll need to do to fix the problem.

What Is Adware?

Adware is a type of software that loads and displays ads on a system, usually in the form of pop-ups, or based on your search requests. It also creates advertising cookies to generate revenue through affiliate marketing.

We should point out that adware is not necessarily malware, and can even have legitimate uses. For example, some 'free' programs display ads to users in order to compensate for their costs (browser games are a great example of this). However, in other cases, adware secretly finds its way into systems. Whether legitimate or not, all adware is a nuisance.

Spyware is another, more dangerous relative of adware, which collects information about your search behavior without your knowledge, using it to target you with specific ads and content.

How Does Adware Find Its Way Onto My System?

Unlike malware, adware usually, but not always, is installed with the user's permission. A few of the most common ways it's transmitted include:

  • Free software
    For many freeware or shareware programs, adware is an important source of revenue. When downloading free software, especially from less well-known or reputable sources, there's a good chance that you'll be installing adware along with the program.

  • Browser extensions
    Free browser extensions can also smuggle adware onto your computer. For that reason, keep an eye on which extensions you install.

  • Drive-by download
    Street gangs use 'drive-bys' to wound or kill their rivals. The download variety doesn't involve any shooting but happens just as quickly, particularly if you visit a site designed to launch the software onto your system. This is also known as browser hijacking.

How to Protect Against Adware?

Most of the time, adware requires your consent to operate on your system. As such, it isn't too difficult to prevent it from doing so. To help improve your chances, we recommend following a few general rules for keeping both adware and malware away:

  • Don't download unknown software
    When surfing online, behave as you do in real life: Be cautious and skeptical, especially about things that seem too good to be true. Educate yourself about programs or software that you want to download and install, and check the source. If possible, read reviews on the programs online.

  • Stay away from dubious/illegal websites
    Nearly every legitimate program is available either from its developer or an official 'mirror', that is to say, an officially recognized site that hosts the files in question. By avoiding the shady parts of the Internet, where illegal software is offered for free, you'll reduce your likelihood of coming into contact with adware or malware.

  • Use an ad blocker
    Ad blockers don't only prevent banners and pop-ups from opening on sites you visit but also stop dangerous scripts from running, which can lead to drive-by downloads.

  • Use antivirus software
    The most proactive thing you can do to keep adware off your system (and all other sorts of malware) is to install and use a solid antivirus program. These don't only scan your system for infections and malware but with their real-time protection features, also keep out unwanted guests (potentially unwanted programs, or PUPs).

How Can I Remove Adware?

If the time for prevention has passed, and adware is on your system, don't worry: You'll need to take some quick action, but, the situation is far from hopeless. Be sure to check out our guide to find out more about how you can get rid of adware.


Adware might not be the worst threat you face online, but is likely one of the most annoying. As long as you pay attention to which software you download and where it comes from, you don't have much to fret over. Should adware have found its way onto your system, you can follow our guide for removing it in a few, easy steps.


What is adware?

Adware is free software that opens pop-ups and other ads on your system. These can influence your search queries and install advertising cookies on your computer, earning affiliate provisions from you.

Is adware dangerous?

Adware is more annoying than dangerous and isn't classified as malware. Some free programs use adware as a legitimate source of revenue. At the same time, adware which makes its way onto your system without your permission, is technically speaking, malware.

Do I have adware on my computer?

The classic symptoms of an adware infection are unwanted pop-up ads (appearing even when not using your Internet browser) and a sudden drop in your computer's performance. Antivirus programs can help you confirm the presence of adware, notifying you of PUPs and removing them.

How can I remove adware?

In some cases, adware can be removed by uninstalling the program that generates the ads. For tougher cases, there are a number of free and paid software solutions available. To find out more about these and how to remove adware, check out our guide.

Janis von Bleichert studied business informatics at the TU Munich and computer science at the TU Berlin, Germany. He has been self-employed since 2006 and is the founder of He writes about hosting, software and IT security.
Continue Reading