Malware (malicious software) is software designed to infiltrate a computer system without the owner's informed consent.
Program that has infected some executable software and that causes that software, when run, to spread the virus to other executable software.
Viruses may also contain a payload that performs other actions, often malicious.
Worm is a program that actively transmits itself over a network to infect other computers.
Worms may also contain a payload that performs other actions, often malicious.
Trojan horse is any program that invites the user to run it, concealing a harmful or malicious payload.
One of the most common ways that spyware is distributed is as a Trojan horse, bundled with a piece of desirable software that the user downloads from the Internet.
Rootkit is a program which modifying the host operating system so that the malware is hidden from the user.
Rootkits can prevent a malicious process from being visible.
A backdoor is a method of bypassing normal authentication procedures. Once a system has been compromised, one or more backdoors may be installed in order to allow easier access in the future.
Spyware is a type of malware that is installed on computers and collects information about users without their knowledge.
The presence of spyware is typically hidden from the user.
Sometimes, spywares such as keyloggers are installed by the owner of a shared, corporate or public computer on purpose in order to secretly monitor other users.
Adware or advertising-supported software is any software package which automatically plays, displays, or downloads advertisements to a computer after the software is installed on it or while the application is being used.
Malware programs install a key logger, which intercepts the user's keystrokes when entering a password, credit card number, or other information that may be exploited. These are then transmitted to the malware creator.
Electronic device that is connected to a telephone line to monitor the dialed numbers and alter them to seamlessly provide services that otherwise require lengthy access codes to be dialed.