Until a few years ago, viruses were the main threat to computers. Viruses are programs that replicate by infecting other files or applications and carry out damaging actions.

Then worms appeared, programs that do not need to infect other files in order to replicate, and which spread by creating copies of themselves in order to collapse the networks they penetrate. To these, Trojans and backdoor Trojans can be added. These apparently harmless programs try to get into computers and steal passwords and capture keystrokes, allowing remote access to the information stored, etc.

However, recently, due to the widespread use of computers and the Internet, other threats have appeared that can be extremely destructive, redefining the concept of threat, also known as malware.

The word malware comes from malicious software, i.e., malignant programs. Malware includes any program, document or message that can cause damage to computers, resulting in loss of data and loss of productivity.

Therefore, as well as viruses, worms, Trojans and backdoors, the following can also be defined as malware:

		Dialer: A program that tries to establish a phone connection with a special rate number.
		Joke: A harmless program that pretends to carry out damaging actions on the computer.
		Security risk: A legal tool that can be used for malicious purposes.
		Hacking tool: A tool that allows hackers to carry out damaging actions on affected computers.
		Vulnerability: A programming error in an application that can be used to breach security and take control of computers.
		Spy program: A program that collects data on the users Internet habits and sends it to advertising companies.
		Hoax: An e-mail message warning of a virus that does not exist.
		Spam: The mass-mailing of unsolicited mail, which is generally commercial mail.

All of these are types of malware that are currently circulating.