Their name signifies that they are potentially harmful to your computer – malicious + software = malware.
They include programs that install on to your computer and consume your system resources to perform their own tasks. Spyware and adware programs with a potentially dangerous side can be categorized under malware.
Keyloggers, Trojans, worms and viruses are just some examples of what malware applications could be.
Right from inducing popup windows all the time and redirecting you to some other website, malware could perform different tasks while infesting your computer and using up its resources. They can be used to send information pertaining to your surfing habits, the files that you download, your email addresses and even personal information like your name, address and phone number.
Typically, a malware application could do anything from providing information to letting a hacker gain control of your system. Keyloggers, for example, record all the keystrokes you make and send them to the host. These include the passwords for your email addresses, bank accounts, debit and credit card details and more.
A Trojan horse lets the hacker take complete control of your system while it is active by creating a backdoor connection between the host system and your system. This can even end in identity theft; multiple cases of Internet identity theft were recorded in the US in the early 21st century.
Malware applications come bundled with one or more of these malicious objects and could even succeed in infesting your system with viruses or worms that destroy files and attach themselves to the root folders. Not only do they render your files unusable, but also they cause frequent crashes and system freezes.
On the other hand, malware applications do not have to have severe implications such as this; any program that collects information pertaining to you and monitors your activities and sends them to the host even for marketing purposes can be referred to as malware. At the least, they open up a portal through which viruses and Trojans can be sent to your computer.
Therefore, it is essential to install an anti-virus program which can remove malware from the system.