What is it?
Software inducing some sort of harm to a user, computer, or network may be considered malware, including viruses, trojan horses, worms, rootkits, ransomware, scareware, and spyware and so forth.

But, you may ask yourself what is the difference between malware and viruses?
Of course, computer viruses already have a history of decades. Initially they were typically built and used to protect certain software from being copied and used for free. Here, we saw the software producer working in fear. This endangerment of the  potential free loaders worked fairly well. In general terms, you could define a virus as software capable of multiplying itself and able to damage your system by corrupting the data present.

In the pre-internet days, viruses were deployed by offline media such as floppy disks and CD-ROMs. In those days, many people used their intelligence to create these viruses. Their intentions were very diverse, but all in all they did not primarily serve an integer purpose any longer.

The end-user could not permit the non-use of a renowned anti-virus solution.

With the rise of the internet, the threat landscape changed dramatically; particularly the way of distribution changed. So-called worms successfully spread through the internet work, infecting tens of thousands of computers in an unbelievably short amount of time. One could say that from that moment onwards a large amount of new techniques - such as spyware, Trojans, adware, ransomware, worms and viruses - were created and used on a global scale; a new era.

The term malware refers to malicious software and is used as an umbrella term to point to the previously mentioned variants.

To conclude, anti-malware is associated with detection and removal of new techniques and new variants used by the attackers. Anti-Virus refers to relatively known attack vectors and techniques used by cyber criminals. Most antivirus companies still use terminology known by the mass: marketing plays a large role here.

Why do I need it?
You probably want a solution which not only detects legacy threats, but is capable of detecting as much malware variants as possible.
Anti-malware typically focuses on detection of new techniques* used by the cyber criminal without prior knowledge of the malware itself (such as signatures).

Here, we find an argument to combine both a strong Anti-Virus solution with an Anti-Malware solution. They may have some overlapping, but overall they complete each other perfectly.

We analyze and advise such a combination in our bundle program.

(* Currently common techniques to detect may include zero-days, polymorphic malware, packed droppers, self-encrypting malware, malicious macros, rootkits and so on.)

How to (not) use it?
Many anti-malware solutions were built bit by bit, adding detection techniques every time a new threat entered the scene. This should not affect the effectiveness of the solution on the whole.

However, it is wise to thoroughly test the solution when a major new version is about to be released. Furthermore, since an anti-malware solution is far more advanced in its detection techniques compared to Anti-Virus products, false positives (lurking) on already-installed Anti-Virus products are (a reality).

Thus, do not carelessly install multiple products assuming that they will complement each other. They could do the adverse and also make your computer sluggish and unstable.