"Malware" is a term that is a combination of the words "Malicious" and "Software" and covers a broad spectrum of miniature applications known as Spyware, Adware, Viruses, Trojans and Worms.

A virus is a self-replicating program that copies itself into other executable code or documents. Based on this, it is a fair assessment to state that a computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells. Following the same analogy, the insertion of the virus into a program is termed infection, and the infected file (or executable code that is not part of a file) is called a host.

Another type of program that is malicious and is generally grouped with the virus category is a "Trojan". Trojans are made up of malicious code tacked onto what appears to be a legitimate program. They wait until a certain time or a specific program to be ran to release itself and can masquerade as a game or utility program that you would knowingly install on your computer. When you least expect it, it will carry out actions such as displaying messages, erasing files, formatting disk(s), spy on you with your own webcam, etc. One of the positive things (if you want to call it that) about Trojans, is that unlike Viruses, a Trojan horse doesn’t infect other host files, thus cleaning is not necessary. In order to get rid of a Trojan, you just simply delete the program.

Worms also fall into the "virus" category, although technically a program can be a worm and not be destructive. By definition, a worm is software program capable of reproducing itself and has the ability to spread from one computer to another over a network. Unlike a virus which attaches itself to, and becomes part of, another executable program, a worm is self-contained and does not need to be part of another program to propagate itself. Worms are often designed to exploit weaknesses in Windows as their means of propagation.

Adware is a software application that can display advertising banners while the program is running or via some other triggering mechanism is called adware. Ad delivery systems are most often integrated into free applications as a way for developers to recover costs or generate revenue. A critical eye has been placed on adware system since in many cases, in addition to downloading ads, they may also upload user information collected without explicit permission. This type of adware is often referred to as "trackware" or "spyware".

Spyware is a term used to describe a program that monitors your actions. While they are sometimes sinister, like a remote control program used by a hacker, software companies have been known to use Spyware to gather data about customers. The practice is generally frowned upon. Secret code hidden in an otherwise harmless program. Spyware permits unauthorized access to a computer, allowing someone else to observe the user, read data, or even control the computer. Spyware is commonly known as malicious software installed on a machine, sometimes with a user's consent. Some software producers and webmasters who offer downloadable content put spyware in executable downloads in order to earn a profit from a third party or track the activity of a user. Many Spyware applications can be removed with free products like AdAware and Spybot Search and Destroy. However, there are others that cannot be, so it is sometimes wise to purchase a reputable application such as Sunbelt Software's Counter Spy.

	There are many tools online that offer to resolve your spyware issues, but not all of them can be trusted. Some claim to find spyware and want to sell you the application necessary to clean the infestations. Others install spyware on your machine when you install their application. Very few free anti-spyware utilities are better than Patrick Kolla's free utility.
	Of course, since no utility is perfect, I also recommend that people use Lavasoft's AdAware utility. This application finds things that Spybot Search & Destroy does not, and vice-versa. The latest release, Ad-Aware 2007, is faster at updating and scanning, and now supports Internet Explorer, Firefox and Opera. There are free and retail versions of this award-winning application.
	Although Spybot Search & Destroy and AdAware 2007 Home Edition are excellent utilities, they are not proactive in securing your system. In order to feel more confident knowing that your machine will not be hijacked, you should have a utility that actively monitors and scans your system. For that, I recommend Sunbelt-Software's CounterSpy 2.0 utility. Although not free, it is a great bargain at $19.95 per year for your update/upgrade subscription, and is offered as a free, full-featured Trial.
	Ewido was recently acquired by GriSoft, makers of the free AVG antivirus application. They offer a free online scanner as well as a stand-alone client version, now known as AVG Anti-Spyware.  Although they have raised the price from $29.95 to $39.95, this now includes a 2 year subscription rather than a 1 year, so the price tag is ultimately cheaper than it was previously.
	Of course viruses are still a big threat, especially for those who use the Internet.  If you do not currently have an antivirus application installed on your PC, I suggest that you try Avast! AntiVirus by Alwil Software. I have found this to be one of the best tools available for fighting viruses, even allowing a "boot-time" scan of your drive(s), which allows you to kill viruses that load into memory when Windows starts. Avast is FREE for home use.
	To be fair, I will also mention that AVG also offers a decent FREE Anti-Virus application.  However, the features are somewhat limited in comparison to Avast and is obviously targeted at getting people to purchase their Anti-Virus Pro or Internet Security Suite products.
	Malwarebytes' Anti-Malware is considered to be the next step in the detection and removal of malware. In our product we have compiled a number of new technologies that are designed to quickly detect, destroy, and prevent malware. Malwarebytes' Anti-Malware can detect and remove malware that even the most well known anti-virus and anti-malware applications fail to detect. Malwarebytes' Anti-Malware monitors every process and stops malicious processes before they even start. The Realtime Protection Module uses our advanced heuristic scanning technology which monitors your system to keep it safe and secure. In addition, we have implemented a threats center which will allow you to keep up to date with the latest malware threats. Activating the full version unlocks realtime protection, scheduled scanning, and scheduled updating. For consumers and personal use, it is a one time fee of $24.95.
	What they claim:  "SUPERAntiSpyware is the most thorough AntiSpyware scanner on the market. Our Multi-Dimensional Scanning and Process Interrogation Technology will detect spyware that other products miss! SUPERAntiSpyware will remove ALL the Spyware, NOT just the easy ones!" My experience:  It catches things that are left behind by running all the rest, so their claim does have some validity.  Add this to your arsenal and your machine will run more smoothly than if you didn't. SUPERAntiSpyware comes in a Free version and an enhanced "Professional" version that is available for $29.95.
	If you feel that you may already be infected, it is recommended that you visit Trend Micro's Housecall website and run their java based virus detection tool. Be forewarned that although this is a good utility, it is very slow and should be started before leaving the house for work or when you're heading to bed.