Still shocked by the number of posts containing at least some form of incorrect information here. About 95% or more from what I have read are in some way stating what they perceive as facts, but are most certainly not.
First, for anyone that is an IT person or has advanced computer knowledge, you already know what I am going to say. Most of the public though, as evident here, simply lack that ability for various reasons.
The discussion/debate over the whole "virus" term is not made clear so let me try to help here. A "virus" is a generic term that is used to describe some sort of malicious code regardless of its behavior. To demonstrate this, take the term "PC" and ask most what this means. Many will respond that it is Microsoft or not a Mac. They would be wrong however, because most ads, articles, etc. do not give proper technical terms since the general public has a basic frame of reference for what THEY believe it means. In contrast, a "PC" is in fact a generic term that is short for "Personal Computer" and it has no regard to a specific OS. It can be a Mac, Windows, Linux/Unix or whatever. This is the correct and proper term despite how the media and such state it to the public and is historically correct. Now, the same thing holds true for the term "virus". This too is a generic term that is used to describe any type of code that does some sort of harm. Where you get the different terms such as "Malware", "Trojan", etc. is all based on how this harmful code acts, spreads, is obtained, etc. Once this is known, then it is put into the various categories you see mentioned mostly.
If anyone truly wants to learn the FACTS and history behind these matters, I would urge you to read known technical sites that are accurate for computer security. The one I know of is Steve Gibson with the podcast "Security Now" that is a national cyber security expert. There are a few others too if you do your research, but they will give more details than you can find here or in most forums.