Trojan Horses:
A Trojan horse, or Trojan, is a type of malware that masquerades as a legitimate file or helpful program with the ultimate purpose of granting a hacker unauthorized access to a computer. Trojans do not attempt to inject themselves into other files like a computer virus. Trojan horses can make copies of themselves, steal information, or harm their host computer systems.

Worms:
A worm is a program that makes and facilitates the distribution of copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism. The worm may do damage and compromise the security of the computer. It may arrive via exploitation of a system vulnerability or by clicking on an infected e-mail.

Bootsector Virus:
A virus which attaches itself to the first part of the hard disk that is read by the computer upon bootup. These are normally spread by floppy disks.

Macro Virus:
Macro viruses are viruses that use another application's macro programming language to distribute themselves. They infect documents such as MS Word or MS Excel and are typically spread to other similar documents.

Memory Resident Viruses:
Memory Resident Viruses reside in a computers volitale memory (RAM). They are initiated from a virus which runs on the computer and they stay in memory after it's initiating program closes.

Rootkit Virus:
A rootkit virus is an undetectable virus which attempts to allow someone to gain control of a computer system. The term rootkit comes from the linux administrator root user. These viruses are usually installed by trojans and are normally disguised as operating system files.

Polymorphic Viruses:
A polymorphic virus not only replicates itself by creating multiple files of itself, but it also changes it's digital signature every time it replicates. This makes it difficult for less sophisticated antivirus software to detect.

Logic Bombs/Time Bombs:
These are viruses which are programmed to initiate at a specific date or when a specific event occurs.

R.A.T.S:
These are programs called (remote administration tools) and these basically do what they say, they can gain access to your computer by downloading one .exe program called a server (they do not have to be called this) and can gain access to anything on your computer, from freezing your keyboard and mouse to controlling what you type and what you click, this operates like teamviewer but the person on the other side is intending to do harm.

Key Loggers:
These are programs which do not control your computer but they do record what you type and send them to the culprit behind creating it with all the information they need to login to the accounts you own, so if you have ever been infected by a keylogger, change your password on thetechgame to prevent your account being banned or stolen.