What Are Adware and Spyware?

What's the difference between them, and how to avoid infection

Adware and spyware are two different kinds of malware, which is any type of software that aims to harm your computer or network. Adware invades your system and displays unwanted advertisements designed to earn money for its author. Spyware, on the other hand, runs secretly, gathering information about its target and transmitting it to another entity.

Here's a look at how adware and spyware end up on your computer, what the infection symptoms look like, and how to prevent these malware miscreants.

Adware and spyware are types of malware, but they technically aren't viruses. Viruses can self-replicate, damaging your system by corrupting files or filling up your hard drive.


Adware is a type of malware that serves up unwanted advertisements, usually in your web browser. It's important to understand the adware's goal, how adware gets on your system, and the symptoms of an adware infection.

Adware is software that generates revenue for its developer by automatically generating online advertisements
Luis Diaz Devesa / Getty Images

What Is the Goal of Adware?

Adware's goal is simple. It wants your money. Adware displays advertisements, redirects your search requests, and collects marketing data to serve up even more customized advertising. The more targeted the ad, the more likely a user is to make a purchase.

How Does Adware Get on a Computer?

You can get an adware infection in a couple of different ways. Adware often hitches a ride on programs you intentionally download, such as utility software or a game. It installs itself surreptitiously, without the user's knowledge.

An infected website can also deliver adware to your computer, taking advantage of a browser vulnerability or a security flaw in your operating system. This is what's known as a drive-by download.

Symptoms of an Adware Infection

If you've been infected with adware, you may notice that your browser's home page is suddenly different. When you're browsing the web, pop-up ads will persistently bombard you with their messages. Websites you visit may display differently, and when you click on a link, you may be redirected to a page you never meant to visit.

New plug-ins and toolbars may appear without your permission, and your browser may start operating very slowly and even crashing frequently. You may notice an uptick in data usage, and software you never wanted may start installing automatically.

You may experience system anomalies or incompatibilities that cause problems with other programs, even disrupting the operating system and slowing down your entire computer.


Spyware is more insidious than adware. It infiltrates your system, gathering your confidential information, including the websites you visit, passwords, usernames, payment information, what you download, and more. Here's a look at the spyware's goal, how spyware gets on your system, and the symptoms of a spyware infection.

Computer keyboard with a magnifying glass, depicting spyware

Spyware's Goal

Spyware is used for many purposes. In its most benign form, spyware aims to track and sell your internet usage data, including the websites you visit, ads you click on, and time spent on certain sites.

At its worst, spyware wants to steal your identity or money. Keyloggers are a type of spyware that records keystrokes or screenshots, sending them to remote attackers who hope to glean user IDs, passwords, credit card numbers, and other sensitive information.

There are benign uses for keyloggers, as well. Some businesses may log keystrokes to track employees' computer usage. Parental control programs may also monitor keystrokes to log a child's internet activity.

Symptoms of a Spyware Infection

Symptoms of a spyware infection often overlap with symptoms of an adware infection, including a hijacked home page, web searches that are redirected to other sites, a crashing browser, and altered computer settings.

There may be an onslaught of pop-up ads, keys not working correctly in a browser, random error messages, and new program icons that appear on your desktop

You may also experience some more sinister symptoms, including files that mysteriously move or disappear and emails in your Sent folder that you didn't send yourself.

Since spyware takes up massive system resources, you may experience overall slowing, crashing, and a system that seems to have a mind of its own.

How to Avoid Adware and Spyware

Before downloading any software from the internet, do some research and make sure it's coming from a reputable source. Be wary of visiting any website that seems untrustworthy.

Never click on a pop-up ad while you're browsing the internet, and especially avoid ads that pop up claiming that your computer is already infected and you should "click here" to solve the problem.

Make sure your operating system and browser are always up-to-date. Outdated systems are more likely to have unpatched security flaws that leave them vulnerable to infection.

Take advantage of security settings such as blocking pop-up ads and scanning any downloaded file for viruses. Get a good anti-malware program to actively protect your system from spyware and adware.