There are various types of malware which include viruses, Trojans, spyware, adware, worms and other malicious programs or bugs. Malware is simply any program that makes, or attempts to make an unauthorized change to a computer and its software or programs.
Here are the definitions of viruses, Trojans, worms and spyware and adware:
Virus: A computer program that is designed to replicate itself by copying itself into the other programs stored in a computer. It may be benign or have a negative effect, such as causing a program to operate incorrectly or corrupting a computer's memory.
Trojan: A Trojan is similar to a virus, except that it does not replicate itself. It stays in the computer doing its damage or allowing somebody from a remote site to take control of the computer. Trojans often sneak in attached to a free game or other utility.
Worms: A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it. Unlike a computer virus, it does not need to attach itself to an existing program.
Spyware: A type of malware (malicious software) installed on computers that collects information about users without their knowledge. The presence of spyware is typically hidden from the user and can be difficult to detect. Some spyware, such as keyloggers, may be installed by the owner of a shared, corporate, or public computer intentionally in order to monitor users.
Adware: Adware, or advertising-supported software, is any software package which automatically renders unwanted advertisements. These advertisements can be in the form of a pop-up. They may also be in the user interface of the software or on a screen presented to the user during the installation process. The object of the Adware is to generate revenue for its author. Adware, by itself, is harmless; however, some adware may come with integrated spyware such as keyloggers and other privacy-invasive software.
I'm often asked, "Why do people create these things?" To be honest, only they can give a clear answer to that. But, in my years of experience in dealing with these problems, I've come to believe that the challenge is what starts it off. Can I just get into someone's system to see what they have on it, or what they've been doing with their computer? Who really knows why they do it. I do know that if these people would put as much of their talent into some-thing truly productive, they would be extremely productive in the field of computers.
Did you know that the first "virus" was actually created as a means of protecting a program from being stolen from two developers? If someone tried to steal the program they were creating, the thief also got something unwanted along with it. The "virus" was designed to shut the thief's system down to the point that the thief would have to re-build their system. It just took one person to take it from there to where it is today.
Hopefully you'll find this information useful and educational.
My name is Don Wood, and I am The Computer Guy.
The Computer Guysupport@thecomputerguyonline.org