The term "malware" refers to any malicious program or code that is designed to infiltrate, seize, or damage a computer without the computer owner's consent (and often times without their knowledge, altogether). The expression is more of a general term referring to any of the various types of malware that are known to be harmful with effects ranging from annoying to hostile and dangerous.
The term "computer virus" is often used within the same context, however this is actually incorrect, as a "virus" is a more specific type of malicious software, whereas malware covers the broad spectrum of harmful programs and codes.
So when does software become labeled malware? Basically any software that is perceived to have been designed with the intent of manipulating or damaging other computers is considered to be malware. The umbrella of "malware" covers many different instances, including computer viruses, Trojan horses, worms, most types of rootkits, spyware, unwelcome adware, and generally any other malicious or unwanted application. In terms of law, malware is sometimes also referred to as a computer contaminant.
Some users make the mistake of confusing malware with faulty or defective software that does not function properly. Malfunctioning or "buggy" software should not be labeled as malware, as it was not created with the intent to damage or compromise the computers that run it.
Some experts believe that malware is far more abundant than legitimate, "friendly" software, due to the rate at which it is created and released. It is estimated that around 100 different types of malware are released every single day, the more advanced of which can go a very long time without being detected.
Malware has several intended purposes, but all of them are considered to be undesirable, if not unlawful. Different types of malware may be used to simply use a computer's resources to further spread itself, or in some cases it may cause irreparable damage to its host computer. Malware in the form of botnets actually turns computers into zombie like slaves that perform tasks like spamming and DDoS attacks by their operators who are often thousand miles away.
How do you determine if your computer may be infected with malware? There are several things that may tip you off about a malware infection, all of them related to unusual performance of your computer. Sudden decreases in PC performance speed, or strange error messages should both be considered red flags that may be indicative of an infection. If you believe that you may have a malware problem, try running a free virus scan. Several types of free scans are available online. While most will not actually correct the problem for free, they will at least let you know whether or not you have a problem, and potentially give you further details about the problem that may prove to be valuable if you decide to attempt to manually remove the problem.
For discovery and removal of spyware and adware, free utilities like Spybot Search & Destroy can be perfectly effective. Good removal tools (like the aforementioned Spybot Search & Destroy) will do a thorough scan of your system to determine if there is any spyware or adware running, and then give you the option of removing it with a simple mouse click. However, you should be aware that certain types of adware come bundled with free applications (especially P2P programs), and by removing the adware from your machine, you may cause the application it came with to stop running properly. Check the terms of service that you agreed to when installing the software to see if it contains a provision stating that you must agree to the use of their adware (which in the majority of cases will not actually be referred to as "adware") in order to continue using the software.
