Adware, malware, spyware, software...what helps your computer and what isn't so beneficial to your system? It can be difficult to tell, and this is especially true of adware. Adware itself isn't harmful on its own, and it isn't always used in malicious applications. While adware can be a close relative of spyware, it can also be used legitimately by reputable programs. How can you tell the difference between real and rogue applications?

What is Adware?

Adware is ad-supported software. Unlike freeware, which allows you to download and use the program free, adware comes with a caveat: if you want to use, you must allow the ads that support the program. The Eudora email client, for instance, is a form of adware in the sense that it is advertising-supported software. But many times, adware is a form of spyware. The difference is that the user gives consent for the legitimate adware program to install, while spyware installs itself surreptitiously. The objective of adware is to track and record your browsing habits in order to sell this data to advertisers for "targeted" advertising.

How Does Adware Enter a System?

You elect to install legitimate adware; you will see a user agreement and/or end-user license agreement, and it is in these terms of use that you are agreeing to display the ads. A legitimate adware program displays these unobtrusively, and you have the option to use the Remove function. In contrast, adware installs without your knowledge and displays nuisance pop-ups. How does adware enter your system?

Some websites harbor trojans and simply visiting these sites or clicking on an ad or image can allow the trojan to access your machine. In the past, sites with adult content were particularly vulnerable to trojans, but today, they are in a much broader variety of sites, including those with gaming, freeware, P2P, and warez content. Searches for trending topics, such as the latest current event, also yield many malicious results. Clicking on these results will direct users to sites that urge them to purchase "antivirus protection." Really, these are rogue programs that will not protect your computer or resolve any security issues.

It is also common for adware to come bundled with other malware when you download a desirable file. For instance, you may want to watch a video and need to download a codec. When you do, a trojan is "piggybacked" in as well.

How Do You Know You Have Adware in Your Computer?

After it is downloaded or installed in your computer, adware is not a stealth application. It doesn't try to hide; that is, its presence becomes very noticeable. The most clear indication you will have is the increase of pop-up ads. While it is not uncommon for them to display pornographic material, they can also relate to topics that you typically browse. Remember, its purpose is to track your browsing behavior and sell that data to third parties. These pop-ups will be obtrusive and can become quite bothersome. Some other signs you may notice include:

• Slower computer performance.

• Difficulty navigating to certain sites. You may be redirected frequently to rogue sites.

Because it is possible for adware to track your browsing habits, thus interfering with your privacy, it is important to remove this form of malware as soon as you can.