Malware is a term collectively used for malicious software which can use for all kinds of computer threats.  

We can consider malicious software as a program which may harm any computer, computer program or even computer hardware.

Malware also negatively affects computer users in many different ways. It can disrupt computer operations, gather sensitive information, prevent access to the computer systems or network and display unwanted advertising on your web browser.

Basically there are three types of malware to be considered. Such as virus, worms and Trojan

Viruses

A virus is a malicious code that infects software and computer files in a computer. It can access to your computer by an attachment of an email, or via USB storage device and also attaching with computer files.

However, most of the time the virus may exist on a system and won’t be active or spread until the user runs or opens the infected file or program.

Virus can do things like

Changing system settings, deleting files, disabling functions, sometimes even hardware damages

Worms

Worms have the ability to damage your computer and move from computer to computer in a network. That means worms do not need human support to spread. Sometimes we can’t find it in the computer because it has already moved to somewhere else.

Worms search for week points in your computer security and make it accessible to malicious programs.

Trojans

Trojan is a malicious code or software that enters your system pretending to be a legitimate software or part of software that helpful for computer user. But the problem is Trojan can contains all kinds of malware.

Trojan allows third party to access your computer and spying on your work.

There are few types of Trojan to be considered.

Backdoor Trojans

Back door Trojan opens the backdoors for uninvited parties to enter remotely to your computer and these are the most dangerous types of Trojan attacks

Keyloggers

Keyloggers steal user’s login credentials and confidential data from any application by recording every key that user press.

Banking Trojans

Banking Trojans are designed to obtain user’s impotent credentials of online banking and payment systems to steal money from user’s bank account.

Trojan-downloader

Trojan-downloaders download malicious codes from a website or a remote server to your computer.

These are the security practices that you can follow to secure your computer or network form the malicious programs.

Install antivirus software and update on regular basis which prevents your computer form virus attack and delete virus that already being in your computer.

Using of an anti-malware program like Malwarebytes 

Install a firewall

Make sure that you open only email attachments sent by reliable parties

Download files only from reliable web sites