Computer Virus: The Types of Viruses Out There
A computer virus is usually hard to detect if it's disguised as a harmless file, in the case of a Trojan horse virus. This type of virus doesn't replicate itself like most viruses, but instead opens your computer up to malicious imposters. Leaving you to wonder, how can you tell if you're computer is infected?
Luckily, your computer after coming in contact with a virus or worm will display some symptoms and signs of infection. It is particularly useful to know the signs that indicate an infection. Because you can unintentionally introduce a virus to your computer at anytime when you run an infected program or open an email attachment. To guard against this you need a good anti-virus program 
Signs of a Computer Infection
Some signs that may indicate that your computer is infected include:
- Your computer functions slower than normal
- Your computer responds slowly and freezes often
- Your computer restarts itself often
- You see uncommon error messages, distorted menus, and dialog boxes
- You notice applications on your computer fail to work correctly
- You fail to print correctly
Types of Viruses
But what are the types of computer viruses and worms that you're computer can come into contact with? The list of viruses is quiet long and complex. So, we simplified the list by mentioning few broad categories of viruses that can put your computer and all your personal data on it, in danger. These computer viruses include:
Computer Viruses
Boot Sector viruses: A boot sector virus infects diskettes and hard drives. All disks and hard drives contain smaller sections called sectors. The first sector is called the boot. The boot carries the Mater Boot Record (MBR). MBR functions to read and load the operating system. So, if a virus infects the boot or MBR of a disk, such as a floppy disk, your hard drive can become infected, if you re-boot your computer while the infected disk is in the drive. Once your hard drive is infected all diskettes that you use in your computer will be infected. Boot sector viruses often spread to other computers by the use of shared infected disks and pirated software applications. The best way to disinfect your computer of the boot sector virus is by using antivirus software.
Program viruses: A program virus becomes active when the program file (usually with extensions .BIN, .COM, .EXE, .OVL, .DRV) carrying the virus is opened. Once active, the virus will make copies of itself and will infect other programs on the computer.
Multipartite viruses: A multipartite virus is a hybrid of a Boot Sector and Program viruses. It infects program files and when the infected program is active it will affect the boot record. So the next time you start up your computer it'll infect your local drive and other programs on your computer.
Stealth viruses: A stealth virus can disguise itself by using certain tactics to prevent being detected by antivirus software. These tactics include altering its file size, concealing itself in memory, and so on. This type of virus is nothing new, in fact, the first computer virus, dubbed Brain, was a stealth virus. A good antivirus should be able to detect a stealth virus lurking on your hard drive by checking the areas the virus infected and evidence in memory.
Polymorphic viruses: A polymorphic virus acts like a chameleon, changing its virus signature (also known as binary pattern) every time it multiples and infects a new file. By changing binary patterns, a polymorphic virus becomes hard to detect by an antivirus program.
Macro Viruses: A macro virus is programmed as a macro embedded in a document. Many applications, such as Microsoft Word and Excel, support macro languages. Once a macro virus gets on to your computer, every document you produce will become infected. This type of virus is relatively new and may slip by your antivirus software if you don't have the most recent version installed on your computer. .
Active X and Java Control: Some users do not know how to manage and control their web browser to allow or prohibit certain functions to work, such as enabling or disabling sound, pop ups, and so on. Leaving your computer in danger of being targeted by unwanted software or adware floating in cyberspace.